Wait, I just remembered something, there was a memory leak all the while, it's caused by the libtheoraplayer (in the TheoraVideoClip class), but since it didn't really cause any problems, I just left it as is.
All we can do now is to wait for the libtheoraplayer author to fix it (the libtheoraplayer project seems to be inactive for sometime already though, so I'm not sure if it'll ever be fixed).