Comment 2 for bug 1271306

Hi Joseph, I thought it was solved.

Here is what I think, If many movies have been thumbnailed, google may be detecting unusual activity and blocking you temporarily.
Try updating only the files with missing thumbnails:
imdb-thumbnailer -u file1 file2 etc...

You told me by mail: "Only did random ones of remaining."
If the problem persist, can you elaborate a little more?