It's not YouTube restricting the iPhone. I tried those videos on my droid and it had the same problem, and droid as you know is run on google, and google owns YouTube. My best guess is what appears to be a YouTube 3rd party "Vevo". Any Vevo video I tried wouldn't work on my droid. My only other guess is maybe it can't support HD videos? However, I would find it mildly humorous if YouTube started encoding video in flash again, just so Steve Jobs would regret his decision to make an enemy of Adobe. "Who's becoming obsolete now Steve Jobs?" Haha but kidding aside, I highly doubt YouTube, or Apple for that matter is restricting the iPhone, as the droid is having the same issue.