Correct - though this is mostly due to there being little/poor hardware support for those formats. Natively the Apple TV (currently, don't know the new model)

Correct - though this is mostly due to there being little/poor hardware support for those formats. Natively the Apple TV (currently, don't know the new model) supports H.264, MPEG4, and MJPEG - all of which are trivially supported by actual chipsets. Matroska/Ogg/Avi aren't as well supported (or well used, tbh.. other than Avi which is a container anyhow)