Youtube doesn't give you the raw video back, it does transcoding to their given standard bitrates/resolution sets. You'll notice this if someone has just uploa

Youtube doesn't give you the raw video back, it does transcoding to their given standard bitrates/resolution sets. You'll notice this if someone has just uploaded a video to Youtube and the only version available for playback is some 360p/480p version for a few hours until Youtube gets around to processing higher bitrates. So whatever you're encoding has to survive that transcode process.