For the past several years, video sites like YouTube and Vimeo have changed how we watch videos online, and Flash has played a very big role in it. However, in my personal experience, Flash has been one of the biggest pain in the browsers, and watching videos has not been that rosy, not just for me but for several others too.
With the official introduction of HTML5 looming around the corner, several websites and browsers have started to implement the new features available in it. One of the most exciting feature in HTML5 is that it has support for streaming videos through the <video> tag, without having to use any other additional resources or software such as Flash.
Both YouTube and Vimeo have officially started supporting HTML5 videos, which is pretty exciting and will definitely shape the future on how we watch videos online. The most exciting features in HTML5 videos is that you can watch it in fullscreen, just like you would do it on a desktop player, and no more buffering, simply jump to any part of the video you want, again this experience is similar to desktop players.
To watch HTML5 supported videos on your browser visit http://www.youtube.com/html5 or go to Vimeo and click on the "Switch to HTML5 Player" link at the bottom of the video page. Please note that you browser has to be HTML5 compatible in order to view the videos. Right now YouTube and Vimeo only support Webkit based browsers, including Safari and Google Chrome, with support for IE with the Chrome Frame add-in installed.