This should help watching mp4-videos (&fmt=18 and 22 or something like that)
from youtube. ffmpeg for fallback for windows. Not idea about OS X side.
(cherry picked from commit fc5f04d8f6c4a79534d4530e4e15ab9a88deaeb5)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>