I usually run my youtube video's in html5 (flash is turned off) and only enable flash if needed (only once in awhile such as interactive maps). Plus without flash it "breaks" those annoying ads.
Even though I run Linux, these computers are older and I got tired of the Internet slowing up because I was trying to run a youtube video with 10 other flash ads running at the same time. It uses up resources. As a matter of fact, my old tower clunker's video card is so old, it won't even run the newer flash at all. I run it only in HTML5 if I want to see any videos at all.
As for my new Cubox, Android runs videos like their tablets do all OK, but I still have it on Android because I'm trying to find a good Linux distro that I like (and works) with Cubox.