vidix: Replace printf with mp_msg

- Make MPlayer more quiet when requested (e.g. when using -really-quiet)
- Additionally change some minor capitalization and "bla:" to "[bla]"

Patch-by: Arne Bochem >arneb.mp ccan de<
Patch-also-OKed-by: Reimar



git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@37203 b3059339-0415-0410-9bf9-f77b7e298cf2