Handle autoplay state and events correctly

[fregante]

Current incorrect behavior on autoplay videos:

• paused is set to false immediately
• the play event is triggered immediately

Correct behavior:

• paused should be set to true after the canplay event
• canplay, play, and playing should be fired at the same time

Source: https://www.w3.org/TR/html5/embedded-content-0.html#handling-first-frame-available

[fregante]

Also, when a new src is set, the event order should be changed:

 loadeddata
+playing
 canplay
 canplaythrough
-play
-playing