mov: Write prof section of tapt tag

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
mov: Emit the correct tags for clcp tracks

Bug-Id: 664

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
vc1: Do not return an error when skipping b frames

This caused mpv (and possibly others) to fallback to software decoding after
seeking a VC1 stream.

Bug-Id: 667

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>