Which codecs does ubuntu-touch support? Can I add restricted-codecs package? I've copied an .avi file to ubuntu-touch, and I can hear it, but I can't see anything.
I'm not sure about any complete list of codecs but in order to play most "oncommon" codecs e.g. mp4 you have to install some libraries. You should be able to play avi if you install the
ubuntu-restricted extras library.
sudo apt-get install ubuntu-restricted-extras
You can read more about it here
You should of course also be aware of the Consequences of using apt-get in ubuntu touch.
That being said I'n not sure if there is any equivalent of e.g. VLC app or anything you can use that wraps the necesarry codecs. Hovever, if you do find one I'm intrested in hearing about it.
Also see simmilar question.