Support SourceChooser plugin in Flash

  The radio buttons were not showing up in the flash player because the
  source-chooser was trying to find the video sources through
  media.children. However, for the flash player, media.children is
  undefined. Instead if we use the player's node,
  we can get to the source nodes.

  Additionally, the flash VideoElement code was not triggering a
  "canplay" event that the source-chooser plugin uses to determine when
  to play the newly loaded media. We trigger both the "loadeddata" and
  the "CANPLAY" events after connecting to the stream since at that
  point, the video will be playable.