o.k., I've tried the "hardware accel." solution(s), the "ad blocker off/on" solution(s), the "clear the cache/memory" solution(s), the "refresh Firefox" and "Safe Startup Firefox" solution(s)....and guess what? Not any one video will load (and play) in Firefox/YouTube. Not any one.... Just a black screen with a white circle that spins & spins & spins, ad nauseum. Meanwhile, Chrome, Safari & Opera will all load and play teh same videos on this same laptop.... But I WANT to use Firefox!! grrrr!!!