No, youtube vids will simply not even play under 2006. You will get the typical flash error message. Under 2007 HE, you can get some audio. I don't honestly know how well youtube plays under HE because I didn't do much testing. The 2006 OS gives you Flash 6 while the 2007 OS gives you Flash 7. The HE page says that the rendering engine doesn't change, but I think they forgot about the flash version upgrade.

Anyway, power management under hacker edition is terrible. It's sometimes hard to tell right away because it's so intermittent. I guarantee you will not be using HE for any extended period of time unless you don't take the thing off the charger. You literally won't get 3 hours of suspend time, let alone usage. It's really aggravating because it seems so small a problem to make HE so unusable. I'm hoping for further development in the mean time.