Why are images on retina display pixelated whereas videos are fine? I just bought MacBook Pro 13" with Retina Display. I have noticed that bitmap images (which are not vector graphics) are pixelated and fuzzy on several websites. However, videos seem to be fine. Why is that so? Can anyone explain why only bitmap images are affected by this (low resolution) but not videos?

For example, when I open YouTube, the logo of YouTube on left corner appears fuzzy, but video is played fine and correct. What method is used in videos then?

Does anyone know?
The videos remain sharp on the retina display because they're scaled down to half their original size (a 720p video is 1280x720, but displayed at 640x360 on YouTube). 

Images on webpages are usually blurry because in order to display at the same physical size as on a non-retina display, they have to be scaled up 2x (unless the website provides 2x source images, like Apple.com does).