When you try to play some video with VLC you have only sound and a black screen for the video.
- Go to menu : Tools -> Settings
- Click on Video on top of panel
- Change output from automatic to X11 (XCB)
So after you can play videos but no hd ones because it's only software decoding.
Fullscreen or resizing window are slow too.
And I have some sound delay but not every time.
I suspect the analog sound output, can someone try with sound over hdmi and tell me if it work ?