I was in a bar and saw that on the 42" LCD TV, the live TV feed was reduced in size to about 37" and was positioned in the bottom left had corner. The rest of screen area around the feed was then displaying advertisements. These were done in flash and would cycle continuously.

I know that the main driver was a mac mini, but there must have been some hardware that intercepted the signal, and some software that was doing the TV resize and overlay.

Any suggestions on how it was done?

Thanks

Not sure on that specific setup, but I am sure there are computer programs that can do that. It would be simple to do really.