The two most important uses of the QTSRC attribute in your EMBED tags are:
1. To force QuickTime and only QuickTime to play any file that QuickTime understands (.mov, mp3, .mid, .swf, .wav, etc..) You can design a page and know that if QuickTime is installed on the user's machine, only QuickTime will handle the file.
See MyQTSRCEmbed.html in the lesson 15 folder
2. The QTSRC attribute is also useful for passing protocols, including RTSP directly to the QuickTime plugin or QuickTime Player. Browsers are not designed to handle realtime streaming protocol directly. Rather, the media player or plugin must receive the request.
Check out FinaleRTSP.htm for an example