I would like to know what effects the picture quality of a video when uploaded to a site(not the quality from the camera). I've noticed that when a video is uploaded to different sites they have different image quality. Such as seeing a video on a .com compared to a site like youtube. Also i've seen that almost all movie trailers are played in quicktime and they look really nice and was wondering if this had to do with format or not. Is video quality based on format/webspace/both?