Totem lacks support in ac3 playback though it seems gstreamer is capable of playbacking it through gst-plugins-a52dec. I believe it would be nice to have an ac3 USE flag just like there's an aac USE flag. About aac - the USE flag exists but totem should have support for it adding faad dependecy for gstreamer.
this bug consists of 2 requests.. the ac3 one i do not intend to implement that way and the other is covered in another bug. closing