yeah, i get no error codes either. my first thought was that it might be a computer problem, since the way the video freezes and starts up again really resembles some kind of regular hangup. but every other process on the computer is working fine. and the xfinity video never actually stops, or results in an error code. it will go on for eternity, it just stalls and restarts probably 3 or 4 times a minute. it really makes using the service impossible.
restarts, refreshes, new browsers, purging cache/history, repairing disk permissions, updating all plugins, etc. haven't helped at all. there's clearly something going on, on their end.