Re: 295.33 or flash bug?
It's a bug in X.org server which is triggered by Adobe Flash.
In this version of Flash Player Adobe developer enabled Accelerated Video Rendering via OpenGL, but it doesn't play nicely with X.org server and NVIDIA drivers.
There must be a way to disable Accelerated Video Rendering, or we'll have to restart X.org server once in a while. Unfortunately nor X.org developers, nor NVIDIA want to solve it.
As a workaround you can downgrade to one of previous Adoble Flash Player releases (however bare in mind that they have known vulnerabilities).
And this problem also manifests itself in video leaking through black parts of other windows.
In short Adobe Flash Player 11.2 is utterly unusable for NVIDIA users.