Logout on Video play

Hello

So, I wanted to try Debiand and I downloaded the hybrid gnome version containing non free firmware:
http://cdimage.debian.org/cdimage/un...64/iso-hybrid/

I wanted to start by using a live session, I was happily surprised that Wifi and mp3 worked right away. But I tried to play a video (mp4/mkv), Debian just gets out to login screen. (The problem does not occur in VM)
I have an Asus laptop with an intel graphic card.

Any one who knows how to fix this problem please?

Thank you