I like to connect a beomaster 5 with beosound 5 on my Avant TV to play computer music on my system.

I have only the connectors on the back of the TV free where I can connect a video camera. (On top of the TV)

Since the same connectors are shown at the back of the beomaster my question is now that when I connect both together via this way what can I expect to be working.

Audio distributed on my surround system connected via the Avant?

Video shown on the TV?

Or nothing at all?

If the AV inputs at the top are the only ones available than you may have an issue. These are "line sensing" inputs meaning that anything plugged in will supersede other connected peripherals. It is meant, as you mentioned, for video cameras and such. 

The real issue is that until late summer or early fall, you won't be able to do this at all. The BeoMaster 5 does not accept commands over ML from Avants or BeoSystem 1s and it won't support an outboard eye until the next major software release.