- Combo pack which includes Perian, WMV and AC3 components. CAUTION: Web page disses Perian.
- Apple MPEG-2 playback codec, which costs money.
Move /System/Library/Quicktime/QuicktimeMPEG2.component to the AppleTV and restart. Tested playing a VOB file from a DVD. Video was extremely choppy but I believe that was because the file was being played from a AFP share mounted across my crappy wireless network.
Note: I've also tried the Apple MPEG-2 codec, but am getting very choppy video over a 100Mbit wired connection (NFS server). It's bad :( I can't tell the different between the wired and wireless playback attempts.
- Vorbis and Theora support (OGG).
-  Open Source Matroska QuickTime Component