The TouchPad, out of the box, only supports mp4 with h.264 or h.264 codecs. To play other formats, you can either purchase KalemSoft’s Media Player, or convert the video to a native format.
I recommend HandBrake for all your conversion needs:
An OpenSource, GPL Licensed, multiplatform, multithreaded video transcoder.
Available for Linux, Mac or Windows, you can get it here.
installing on Linux Mint/Ubuntu:
# add-apt-repository ppa:stebbins/handbrake-releases
# apt-get update && install handbrake-gtk
The easiest method involves selecting your source in the upper left, choosing the file you wish to convert, and utilizing iPad as a preset on the right hand side. If you have multiple videos you’d like to convert, you can add them to the queue to process while you go and find something else to do. Once the conversion is complete, you can copy the file over to your TouchPad via USB.
Now that your m4v file is on your Touchpad, tap the Photos and Videos App.
You should find the file listed (Currently, no thumbnail view for movies created this way).
Voilà! You can now watch your movie on your TouchPad.