The sink used for video playback does not do any rendering by itself. It just lets the application get hold of egl images so it can blit them.

The sink uses android GL drivers so not all color formats are supported.

If someone wants to do a video player with GStreamer directly then I can help.

Alternatively have a look at the sailfish media components RPM and there should be a video element that handles all this for you (not supported)

EDIT:
Yes we disabled a lot of codecs and we use AAC encoder only from gst-ffmpeg. The rest has been disabled because it's not needed and because of the limited codecs that we enable in our libav

libav is used for thumbnailing, tracker indexing and some audio encoding and decoding.

EDIT2:
Gallery is not really crippled. The issue is tracker does not recognize all the formats because libav lacks support for them.