I am looking for a program that can play up to 9 videos simultaneously in the same window (16 would be even better). If possible, free and works with Windows 7 SP1 x64 Ultimate. I don't want to have to pre-process the videos to make a single split-screen video. It support the most common video formats.
E.g. (with 4 videos):
For YouTube videos, I can use http://www.swigview.com