Actually, I have same problems, but they manifest itself only with some videos/channels. Other video download software (video download helper for iceweasel/firefox, for example) got same problems, while other don't (flashGet experimental media downloader component works fine).

Considering, that it was working before with exactly same device/versions settings on my side, and that such issues were known to appear in the past (for example, vevo channel on youtube was unavailable for all downloaders, for a whilej, I bet that it is googletube changing things on their side, after all.

/Estel