I'd like this, too. Wish the built-in Youtube app allowed us to set it to "always" play HQ. Seems strange that they'd even want to default to the low-res version considering the Droid's beautiful high-res screen. Maybe they did it for battery or bandwidth reasons?
Oh, that's interesting! I hadn't noticed that and will have to test it out on my home network. I've connected to my home Wi-Fi a few times but must not have watched any Youtube vids or I would've remembered that.