Youtube (recently) limited (again)?

About a month ago, I watched some Youtube videos from my new iphone 4. I had experienced limited search results on a friends iphone before I got my own, but the videos that I was looking for, which were a couple of official music videos, were available on my own iphone at that time.

However, when I search for them now, my iphone 4 can't find them on Youtube. It'll find the Youtube link on Google through Safari, but when I choose that, a message pops up telling me that the movie is unavailable. The mobile version of Youtube doesn't work either, the search results are the same (limited), and the 'desktop' version avaiable in Safari tells me that I need Flash Player. I know it's unavailable for the iphone.

Again, I am 100% sure that I watched these videos on my iphone in the past, using the Youtube app.

Any explanations, other than copyrights or converting (which should've been finished in 2007 apparently)? Everything that I find on Google dates back to 2007, but has the limit been lifted and reapplied in 2011? Does this have anything to do with maintance, will Youtube be unlimited again in the future? Any ideas?

(I am using the latest versions of iOS and iTunes, and Windows 7)

Thanks in advance.