quicktime only works using rtsp off campus

I am running a quicktime 10.3.9 server behind a pix firewall. Quicktime is streaming on port 80. Firewall has port 80 open and is not running a web server. On campus I can connect to the server via http://server/presentation.mov But off campus I can only connect by putting rtsp://server/presentation.mov . When I use http://server/presentation.mov quicktime just says "connecting" but never does.