Hmm, that's strange. To be honest, I don't know what could be going on, I'm sorry, and I don't have a Linux machine to test it on. The tester I sent the build to didn't report that error.
If it won't let you go full screen and you can only play in windowed mode, maybe that's where the problem lies, but I'm not sure.
There are many other problems that could be the cause. 
Can you see the text but not the videos?