Today I wanted to make an embedded YouTube video autoplay. But when I add "?autoplay=1" to the end of the YouTube url in the embed code, it doesn't actually make it all the way through to the HTML given to the browser. Instead, I see a "?wmode-opaque" get stuck onto the end by the PHP code, and anything I've put there gets removed (more accurately, fails to get preserved).
The problem seems to be in models_html5/youtube.html, which creates an "iframe" variable with a bunch of default attributes set to 0. There's some code in the buildIframe function that would add the parameters back in if the attributes were non-zero, but there doesn't seem to be any place in the code where the attributes' initial values can ever get changed--they're not passed in via the page settings (there are no page settings for these), and they're not parsed out of the embedded YouTube URL.
Is this a bug, or is it intentional?