[drsli]

Originally Posted by SighK

Never mind it has resolved itself. It appears videos that are very recently added to youtube will display that error via this addon. So make sure the video that you are trying to add is well and truly processed on youtube.

First of all: this is a truly awesome addition!
I stumbled upon this "The response of the video-server can't be read."-error recently and I had chmoded the thumbnail- and serviceapi-directories accordingly long before. A couple of videos were added without hassle before, but now for seemingly no reason this error occurs.
The youtube-video, which causes this error, is correctly listed and playable within youtube itself. And I can add this video without problems to vbtube too. So this seems to be a video-directory-related issue.