VLC Media Player
DePaul faculty will be pleased to know that the VLC media player is now installed on all classroom PCs again (thanks to Joshua Luttig from IS for the update). The VLC Media Player is a “free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVD, Audio CD, VCD, and various streaming protocols.” - In other words it plays pretty much any video file out there.
On classroom PCs, look for it under:
Music & Video / VideoLAN