Just checks that the 'keepvideo' option works as intended.
They have been available in ffmpeg since version 0.9, and we require 1.0 or higher.
We should look at height and width before ext_preference.
A workaround for video jumping back in time.
Player-url only needed for rmftp, not for regular URLs
Fixed code conventions (mainly adding two or more spaces before making an inline comment)
Implements #3638
720p @ 1000KB/s looks way better than 1080p @ 500KB/s