Another Standards Victory: YouTube Videos via HTML 5
HTML5 includes support for video and audio playback, so users with an HTML5-compatible browser, (and don't forget their computer has to support the proper audio and video codecs) are able to view a video without needing to download and install a browser plugin.
The YouTube experiment does have some limitations. It doesn't support videos with ads, captions, or annotations and the viewer must use a browser that supports both the video tag and h.264 encoded video (such browsers include Chrome, Safari, and ChromeFrame on Internet Explorer).
If you'd like to see the experiment in action, visit the YouTube HTML5 Video Player page. Doing so will allow you to join the experiment and will enable HTML5 for your browser (even MSIE if you use the Chrome Frame).
To try it out, go to the HTML5 page via TestTube or visit this page and join the experiment. This will enable HTML5 video for your browser, provided that it's one of the browsers mentioned above and fits in with the parameters we already referenced. (If you've opted in to other experiments, you may not get the HTML5 player.) You can also enable Feather along with HTML5 video for an even simpler, faster YouTube experience. Their "Feather" project was created to serve YouTube videos with the lowest latency possible by "severely limiting the features available to the viewer and making use of advanced web techniques for reducing the total amount of bytes downloaded by the browser." Sounds promising!
Google is very optimistic about HTML5 as an open standard and wants to be part of the standardization and acceptance of HTML5.