Streaming On Demand Video on Port...?

Dear Folks:

It seems like everyone streams on Port 80. Is this true?

Quicktime Server wants to stream on Ports 554, 7070, 6970-6999, I believe. Are these routinely blocked by routers and firewalls? Is it foolhardy to use these ports?

I want to stream (real stream, not progressive download) and would like to leave Port 80 alone. I also want people in their homes to access my video without problems.

What do people do? Does everyone just end up streaming on 80?

(Will be streaming MPEG4 via OS X Server on Xserve.)

Thanks

Yes, port 80 for websites. But it seems lots of people (most) funnel their streaming through 80 to avoid firewall concerns. Just how common is this practice?