If Youtube videos do not play reload the page, that's a Youtube bug.
Or maybe now, a few years later, it's a new bug ;-)

Massive Attack - Paradise Circus (Zeds Dead Remix)

Agnes Obel - Riverside (Lars von Qualen Remix)

SKisM - Experts

Foreign Beggars - Get a bit More (SKisM RmX)

Droideka - Get Hyper