i\'m trying to build a video player, that works everywhere. so far i\'d be going with:
According to the spec
Dynamically modifying a source element and its attribute when the element is already inserted in a video or audio element will have no effect. To change what is playing, just use the src attribute on the media element directly, possibly making use of the canPlayType() method to pick from amongst available resources. Generally, manipulating source elements manually after the document has been parsed is an unncessarily complicated approach.
So what you are trying to do is apparently not supposed to work.