Youtube – Keep full screen while switching to other app

It turns out that you can add the same zoom information to the query string of the Full Screen URL. Just append something like &zoom=7 at the end of the query string.

For example:

http://www.wunderground.com/cgi-bin/findweather/getForecast?brand=wxmap&query=35.123456,-90.987654&zoom=7

From what I've learnt finally, there's no way to do it. But that's really unfortunate.

EDIT: Although not what I really hoped for, VLC media player actually allows you to view YouTube videos in their original resolution.

1. Open VLC

2. Go to Media (menu) → Open Network Stream... → paste the YouTube video URL in field under the label Please enter a network URL: and hit Play.

3. When the video has loaded, play the video, right-click on the video, under Video (menu item) → select Fullscreen option; then right-click again, and under the same menu item (i.e. Video) deselect Always Fit Window option.

4. The video should now be playing in its original resolution.