Oh well, I understand the problem now
That's so bad....
If I do not uninstall mp4 Demuxer, my mp4 videos are not playing correctly (there are some artificial pixels showing and it's lagging and audio is playing very badly...)
But if I uninstall mp4 Demuxer, it suddenly stops working...
Well, I will try to play with it for a while, maybe I come up with a solution
