Originally Posted by Lamieur
Adobe makes a plugin for a user process. It can only use interfaces provided by the system. If a user process can freeze your system, this is a system problem and a security threat.
That's why I wrote "seems", because it's not a real system freeze. The system recovers by simply killing the process.
Edit: I noticed however, that in order to be able to play videos normally again I have to restart the comp (I haven't tried to unload the driver or restart X tho).
When the "hang" happens, the CPU is divided 50% Xorg, 50% the flash process.
I suspect flash uses VDPAU in a wrong way and leaves it in a bad state. When other apps try to use VDPAU again they can't for this reason.