Here is a guide to install the YouTube lens on Ubuntu 11.10. The YouTube lens allows you to search for videos on YouTube using your Dash menu. When you found a video you like it will not be played in your media player but it will be opened in your internet browser. You can install the lens using the atareo PPA for the YouTube lens.
To add the PPA and to install the YouTube lens open a terminal window (press Ctrl+Alt+T) and copy+paste the following lines:
sudo add-apt-repository ppa:atareao/lenses
sudo apt-get update
sudo apt-get install lens-video scope-youtube
When the lens is installed you can close the terminal window. To enable the lens you need to log out and log in, to use the lens press the SuperKey or Alt+F2 and click on the play icon. Search for the video and when found click on the preview image and the video will be opened in your default internet browser.