I also know we are debating and the reason i debating is because i itself do MPEG4 compression on my videos to keep my videos in good quality and also resize the video.
Actually i am a tutor and i run youtube channel on networking videos when i tape videos in .avi files from my computer it will ends to some 3, 4 gbs but i compress those videos im MPEG 4 technology video qualities will remain same but it will ends to some 4, 5 mbs by which i able to easily upload those videos on youtube.