Hi... welcome to the forum. I think you are the first (??) U-verse user.
I moved the topic to the english section
VIP 1216 boxes are more common in the UK than Germany...
about your question:
you need to understand that all Mediaroom Boxes have tight security in place that prevents any kind of change on the firmware.
we have developed a hack to disable this security by using a microcontroller to patch the memory during boot.
so if you need to build this modchip circuit if want to do anything that is not intended by MS.
about your story of switching to a certain channel to see the camera output... well, that is highly unlikely for several reasons.
however depending on the possibilities of those cameras it might be possible to create some additional GUI parts that would spawn a video stream player to show the camera output, but that would require the camera output to be accessable via network and in a format that could be rendered by the Mediaroom boxes.