I started using smplayer, recently, but there was a problem, 480x360 mp4 videos have no video playback, only sound, however other mp4 files play correctly. But when I use mplayer it plays correctly with video and audio.
I also posted this in ubuntu forums:
Edit: Solved, deleted the ini file opened a random video and when the window that asks for mplayer version appears I chose version 1.0 rc3 or more recent I had put version 1.0 rc1 or more recent, don't know how the hell this solved the problem, but it's solved. XD