I have a brand new Windows 7 64-bit laptop. I was able to watch a flash video just last night, and even watched a youtube video just before (no longer works). I went to use the Gmail calling feature and it said Flash should be installed. I thought NoScript was blocking, but it wasn't. I then went to a flash game site and it wasn't working. I even disabled NoScript at the addon manager and it didn't work. I've currently un and re-installed Flash about 5 times with no luck and no idea what's wrong...
I've had this issue on installs of windows 7 before. Make sure you completely uninstall flash first, restart machine, then install flash.