Here is a guide to install Minitube on Ubuntu 11.10. You can install Minitube using the Ferramosca Roberto PPA for Minitube.
To add the PPA and to install Mintube open a terminal window (press Ctrl+Alt+T) and copy+paste the following lines:
sudo add-apt-repository ppa:ferramroberto/minitube
sudo apt-get update
sudo apt-get install mintube
When Minitube is installed close your terminal window and to start Minitube press the SuperKey and type: minitube
Minitube is a YouTube desktop application. With it you can watch YouTube videos in a new way: you type a keyword, Minitube gives you an endless video stream. Minitube is not about cloning the original YouTube web interface, it aims to create a new TV-like experience.
Read more about Minitube.