Better guards against crashing in video thumbnailer: Bug #739396

For user's video, GStreamer is returning a ridiculously small buffer
(66 bytes) for a frame it reports to be 1920x1080.  Since Totem's
thumbnailer works, presumably there's something wrong with ours, but
these changes at least prevent the thumbnailer from crashing deep
inside GDK pixbuf.
Fixed Russian translation
Some fixes in Russian translation
Prevent video thumbnailer from hanging on malformed vids: Bug #741821

Bogus 100-byte file was causing video thumbnailer to hang during pre-
roll.  Failure to retrieve duration of video is a good clue that the
video itself is not valid for thumbnailing.