At least right now-its the only one that let's me watch and hear youtube video's. Whatever firefox has going on, when I use it to visit certain video sharing sites, I'm getting no sound. I've tried it with Flash both enabled and disabled and neither worked. So I had to use IE and Flash.
Its a dying platform.
True enough, there just does not seem to be any kind of a solution to a problem that is fixable.
When you get the "no sound" thing, try looking at the actual volume of the embedded video which is giving you no sound. Wave your mouse over it. I had the same problem and was appalled to discover that the auto setting must be at zero volume.