Recently, after an upgrade to Adobe Flash (10.2, I believe), all of the videos that I would want to watch in Firefox would exhibit the following problem:

As you can see, the screen was split vertically with a nice green bar across the middle.  In both, the picture is distorted.  Even at full screen, it was very much unbearable.

In resolving the issue, I tried the old standby of reinstalling the software.  Full uninstall, full reinstall.  No change.  Several searches proved fruitless as well.  But, I think I may have been searching with the wrong search terms.  My first searches, I was searching for “flash broken firefox”, “video broken firefox”, and the like.

Finally, today, I did  a search for “flash split video firefox” and happened upon a result in the [H]ardOCP forums that mentioned something that sounded similar to what I was experiencing.  The fix?  A simple setting in Flash.

• To fix the problem, right click on the video while it is playing.
• Click on settings
• Uncheck the “Hardware Acceleration” check box (like you see in the picture at right)
• Reload the page.

That’s it.  Video works perfectly for me now.