Rated 2 out of 5 stars
I found that all my video laggued too much every 10 seconds. After searching on the Net about Firefox, I changed everything I found in about:config with no result.
I tried to launch Firefox without any extension and my videos worked very well. Then I tried to desactivate my add-on one by one, and I found that this one (Long URL tool) was at the origin of my issue....
I don't know why but your script seems to create a lag every 10 seconds when watching a video (Youtube, Facebook, ...)