MacBook Pro OS x 10.6.8/videos don't work Firefox

I am using a MacBook Pro/ OS X 10.6.8---All of a sudden videos on websites do not work on Firefox---They do work on Safari, (but I do  not want to use Safari---It does not work as well on my computer and also takes up alot of space).  Your website says I have the most current version of Adobe Flash installed on my computer.

Thank you---