YouTube CSS Error 2012-03-24: unknown property “transition”

<iframe title="YouTube video player" class="youtube-player" width="640" height="385" src="http://www.youtube.com/embed/Pg7xDVLtapo?rel=0"></iframe>

Timestamp: 2012-03-24,Sat 12:15:09
Warning: Unknown property 'transition'.  Declaration dropped.
Source File: http://s.ytimg.com/yt/cssbin/www-embed-vflrbsSPR.css
Line: 1

Timestamp: 2012-03-24,Sat 12:15:09
Warning: Error in parsing value for 'background-image'.  Declaration dropped.
Source File: http://s.ytimg.com/yt/cssbin/www-embed-vflrbsSPR.css
Line: 1