Player still preloading video tag data

[jeroen]

It occured to me the player is still leaving the "source" of a video tag untouched. This leads the player to pre-load a video in all browsers. This is highly unwanted. On Safari, it's even possible to crash the browser when loading an OGG file into a video tag.

Fixing this would be one of the main reasons for people to use our player over a straight video tag (see  Gruber's comment on this).