Comment 2 for bug 796162

I just stumbled across this blogpost: http://www.glasen-hardt.de/?p=1254 Unfortunately, for some of you - but not for me *g* - it's in German). https://launchpad.net/~glasen backported nspluginwrapper 1.4.2 and made a PPA for it. The current version of nspluginwrapper in Ubuntu Natty is 1.2.2 (more than two years old).
I've added his PPA, updated nspluginwrapper to 1.4.2, disabled the sevenmachines PPA with the old Flashplugin and installed the current flashplugin-nonfree from the Ubuntu repositories (10.3.181.26), and voila! It works. I tested some pages (where I remembered the flickering) and all display issues where gone.
So actually this could be a problem of nspluginwrapper.

You find the PPA here: https://launchpad.net/~glasen/+archive/nspluginwrapper