Oct 27, 2010 13:57 GMT  ·  By

Google is a big supporter of HTML5, but for YouTube it's sticking with the Adobe Flash Player as the default, at least for the time being. Still, it's continuing to invest in its HTML5 player, which it has been testing since the beginning of the year, and is now testing it in the wild in some cases.

Users are now entered into the HTML5 trial over at YouTube even if they haven't explicitly opted to be a part of it. This means that if you're using a modern browser you may start to see some videos served by YouTube's HTML5 player, encoded in Google's WebM video format.

The Google Operating System blog, which noticed the fact that some users were automatically opted in, quotes the YouTube experiment's page as saying:

"You are in a trial for HTML5 video on YouTube. Some users of supported browsers are automatically entered in to the trial. If you wish to leave the trial, use the link at the bottom."

However, it seems that for those who haven't been automatically introduced, the old explanation is still presented.

"This is an opt-in trial of HTML5 video on YouTube. If you are using a supported browser, you can choose to use the HTML5 player instead of the Flash Player for most videos. Your comments will help us improve and perfect the mixtures we're working on," the YouTube page reads.

In the months since YouTube introduced the initial HTML5 support, browsers have been getting better at handling this type of content. The YouTube HTML5 player works in Firefox 4, Google Chrome, Opera 10.6 and above, Safari 4 and above, the latest Internet Explorer 9 beta and in IE 6, IE 7 or IE 8 using the Chrome Frame plugin.

The choice of codec, WebM vs. H.264 depends on your browser. YouTube will default to WebM but if the video hasn't been converted to the new format, H.264 will be used.

Of course, if you're using Firefox or Opera, which only support the open source WebM, some content may not be available so you'll be reverted to the Flash-based player. Another important restriction is that the HTML5 player only shows up on videos which aren't monetized, i.e. have no ads.