Has anyone had any luck with this yet yet?  I haven't, am I missing 
anything?  Or does Apple's RTSP proxy need to be ported to NetBSD? 
(It's currently available for IRIX 6.x, Solaris 2.x, RedHat Linux 5.0 
x86, and Cobalt Linux mips.)  I've included the relevant info from 
Apple on this topic below:

http://www.apple.com/quicktime/resources/qt4/us/proxy/proxy.html

    Firewalls and QuickTime 4
 
    Firewalls designed to protect corporate information can also prevent
    you from viewing QuickTime audio or video streams transported using
    the RTP/RTSP protocol. This is because firewalls are frequently
    configured to block any data protocols which are not specifically
    allowed by your firewall administrator (while RTP/RTSP are recognized
    industry standards, they are rather new). If you are having trouble
    viewing or listening to content streamed from the QuickTime
    Showcase on the Apple web site visit the QuickTime Troubleshooting
    page.
    Recommendations for Firewall Administrators
    QuickTime follows the conventions of the RTP and RTSP internet
    standards to stream media over the web. To enable QuickTime 4 to work
    properly inside your firewall, please follow the following [11]IETF
    recommendation:
 
    Open port 554 for RTSP/TCP data.
 
    Open ports 6970 through 6999 (inclusive) for RTP/UDP data.
    For more information on the RTP and RTSP internet standards:
      RTSP:
    http://info.internet.isi.edu:80/in-notes/rfc/files/rfc2326.txt
      RTP:
    http://info.internet.isi.edu:80/in-notes/rfc/files/rfc1889.txt
    Recommendations SOCKS Administrators
    If your organization uses SOCKS to pass data through the Firewall, you
    will need a SOCKS Version 5 server to pass RTP/RTSP streaming traffic.
    We have confirmed operation with the Aventail SOCKS server, though
    others should also work. NEC has a terrific web site containing
    information about SOCKS Version 5 at http://www.socks5.nec.com/
    Recommendations for Proxy Administrators
    If your organization uses application-specific proxies (e.g. HTTP, FTP
    proxies) to pass data through your firewall, then you will need an
    RTSP proxy for the streaming traffic. Apple has created such a proxy
    and made it available in source code form.
    User System Settings
    For either Socks or RTSP proxy settings, you will need each user enter
    information about your specific proxy configuration.
 
    Recommendations for Vicomsoft users
    Vicomsoft's SoftRouter is the first NAT software router to offer
    transparent support for QuickTime "streaming" of live video and audio
    over the Internet. Previously, Vicomsoft engineers have been working
    closely with Apple to implement a solution that allows multiple LAN
    users to access video feeds through a NAT router as they would any web
    site. For more information go to Vicomsoft's [16]web site.
 
    If you have a home or small business network in which several
    computers are connected to the Internet through an ISDN, ADSL, cable
    modem, or other high speed connection, you may run into problems
    accessing QuickTime movies streamed with the RTP/RTSP protocol. If
    your access device performs 'network address translation', allowing
    multiple computers at your site to share a single IP address, then you
    will need that router to understand RTSP.
 
    You can solve this problem in a number of ways:
 
    Don't share IP addresses; get a real IP address for every
    host that needs to see streamed content. This could be statically
    assigned, or assigned using DHCP.
 
    Contact your router vendor for a software update.


http://www.apple.com/quicktime/developers/rtspproxy.html

RTSP/RTP Proxy Tool Read Me

      The RTSP proxy is an application-specific proxy which would
      normally be run in a border zone or perimeter network. It is used
      to give client machines within a protected network access to
      streaming servers outside that network, in the case when the
      firewall blocks RTSP connections or RTP/UDP data flow. The firewall
      perimeter network is usually configured to allow:
 
      * RTSP connections from within the network, as long as the
        destination is the proxy
      * RTSP connections to outside the network, as long as the source is
        the proxy
      * RTP datagrams to and from the proxy to the inner network
      * RTP datagrams to and from the proxy to the outside
 
      The proxy usually sits within the perimeter network, between an
      'inner skin' and 'outer skin', which have different configurations,
      of course, to allow the flows above.
 
      Note that RTSP runs over TCP; the normal connection port is 554
      (but see below). Note that if the URL supplied by the client to the
      proxy includes a port number, then the proxy will attempt to
      connect to the server using that port number rather than the
      default 554.
 
      RTP runs over UDP, and a range of ports may be used. Client-side
      ports are usually in a restricted range (starting at 6970), but
      servers cannot so easily restrict what ports they use. For safety,
      do not restrict port number access to the RTSP proxy; use only the
      IP address.
 
      Note that this proxy handles standard RTSP controlling standard
      RTP; RTSP can be used to control other media protocols, and is used
      by a number of companies to control proprietary media protocols.
      This proxy does not attempt to proxy those other protocols. For
      more information on these protocols, consult the Internet
      Engineering Task Force documentation:
 
      RTSP:
      http://info.internet.isi.edu:80/in-notes/rfc/files/rfc2326.txt
      RTP: http://info.internet.isi.edu:80/in-notes/rfc/files/rfc1889.txt
 
      Platforms
 
      The RTSP Proxy has been built for a variety of platforms, including
      * IRIX 6.x
      * Solaris 2.x
      * RedHat Linux 5.0 x86
      * Cobalt Linux mips
 
      License
 
      The proxy is supplied to you by Apple Computer under license. The
      license is included in the download, and can be inspected by
      [7]clicking here. You must agree to the license in order to build
      and use the proxy.
 
      Credits
 
      This proxy includes software developed by the University of
      California, Berkeley and its contributors; that included software
      is the regular expression code developed by Henry Spencer.
 
      How To Use
 
      The application must reside on a machine that can see both the
      Internet, and your internal network. This would be your Bastion
      Host, or another machine in your Perimeter Network.
 
      Install the RTSP Proxy in a reasonable place on your machine. Edit
      the qts_proxy.conf file and put in the appropriate place for your
      machine (see below). Launch the application.
 
      For your client machines: Open the QuickTime (Win32) or QuickTime
      Settings (Mac) control panel. Select 'Proxy' from the popup menu
      and then select the [ ] Use Proxy checkbox. Type in the name of
      your proxy server in the Name: field, and the port you configured
      in the qts_proxy.conf file (or 554 as a default).
 
      UNIX
      Put qts_proxy.conf in the /etc/ folder.
      Launch the rtsp_proxy application (ie. #/sbin/rtsp_proxy)
      Use the -s command line option for constantly updating status.
      Use the -h command line option for a description of the other
      command line options.
      NOTE: You must run as root to enable the default port 554 for
      reception.
 
      How It Works
 
      The RTSP Proxy listens on ports you specify for a RTSP command
      sequence. It parses the commands and redirects the command to the
      desired server. It also rewrites the RTSP commands to reflect the
      new set of port numbers that the proxy must use.
 
      The RTSP Proxy will only relay data that comes from a server that
      the data was requested from.
 
      Download
 
      Download the [8]Proxy Source here. It is a shell archive, which,
      when run, will present the license and then decode and unpack the
      proxy onto your Unix machine.
 
      How To Build
 
      UNIX
      cd proxy_unix
      make [sun|sgi|linux|rhap]