1e133943_HTML_5__Preconditions
[Event name] canplay [Interface] Event [Dispatched when...] The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content. [Preconditions] 
readyState newly increased to HAVE_FUTURE_DATA or greater.
HTML 5
Preconditions