Why do Youtube videos play slowly in Firefox?

I’ve been having a recent issue with Youtube videos playing slowly when using Firefox version 33.0.2.
Answer #1
Not an issue here (btw, the latest version of FF is now 33.0.3).
Are you using HTML5 or flash when playing a youtube video?
Answer #2
I am using Flash.
Answer #3
Well… this is going to sound less than helpful, but have you tried uninstalling flash and reinstalling?
Don’t use the normal uninstall process though …
http://www.majorgeeks.com/files/details/adobe_flash_player_uninstaller.html
Grab the uninstaller tool from above as it does a way better job in cleaning up what the normal uninstall leaves behind.