In my Google Chrome I narrowed down the problem. Flash is out for me and pnwd ;D
I take back my words, it was flash. Canged to HTML5 and wonderful even in HD.
Nothing to do with google, with avast, just flash…
No hiccups, no stutter, no problems. So go here and change over: https://www.youtube.com/html5

avast! rocks…

polonus