If you want to watch YouTube videos without using Flash you can – thanks to neosmart.
Available as both a webpage AND as an extension for Chromium (and shortly to work on Chrome), Firefox and any other borwser that supports UserScripts.
Simple go to http://neosmart.net/YouTube5/ and enter the URL of the video you want to watch and it will load in glorious HTML5 playback. (working buttons!!)
If you choose to install the extension you will see a link when navigating YouTube offering to load it in HTML5 via the sit above. Nice!
Google Chromium on Linux now supports the installation of greasemonkey/userscripts AS extensions. SO click on this and you’ll be prompted to install it.