What is the best way to distribute an audio/video feed from a computer to TVs over existing indoor coax cable?
ZeeVee's ZVBox solution is designed exactly for this - hotels, airports, companies etc use this. They can scale massively, they can take video or feeds from PC's and distribute one or both on different channels to existing HDTV's.

So what are you looking for that would be better?  It appears to cover all your bases.