For anyone having problems downloading or even playing videos, I found a little kink that was causing these same errors for me.
After install everything would work just fine until I tried to change playback quality options. Anytime I changed them from default I had problems. Try clearing data and uninstall, then reinstall but don't touch any playback quality settings. I'm willing to bet it'll work just fine after that.
Try this :
~ Sent from a Galaxy far far away ® [HHead]