Recent Version of Flash lags for certain videos on Mac

Hi,

I'm on Mac OSX 10.6.8. I recently switched from Chrome to Firefox and therefore have switched from chrome's built in flash to firefox's external flash. Unfortunately, all recent versions of flash are very laggy for certain videos online.

This does not happen for html5 videos, and does not seem to happen for all flash videos, but definitely happens for a lot of them, and it makes them nearly unwatchable.

For example, this video:

http://www.colbertnation.com/the-colbert-report-videos/428377/august-0 6-2013/stephest-colbchella--013---time-to-dance?xrs=synd_facebook_0807 13_cn_20

Lags every 5-10 seconds, which consists of the video stopping for about 1 second, then catching up. It's pretty annoying.

I've tried:

-turning on/off hardware acceleration

-uninstalling/reinstalling

-restarting computer

-resetting firefox

I haven't been able to figure out how to turn off protected mode, which I have heard may help--but this may be because I'm on a mac and this doesn't exist on macs? In any case, I haven't been able to find instructions to turn this off on a mac.

The only fix I've come up with is downgrading to version 10.3.183.11, which is obviously unsafe. However, this does tell us that the problem is with flash, and that something about the more recent versions is causing it.

Any help is appreciated!