Miro is a free HD video player.
It can play almost any video file and offers over 6,000 free internet TV shows and video podcasts.
Miro has a simple, gorgeous interface designed for fullscreen HD video. Since Miro downloads most videos, you can take your shows with you, even on an airplane. Quite simply, Miro is a better way to watch all the video you care about.
Best of all, Miro is 100% free and open source, developed by a non-profit organization and volunteers around the world.
To install Miro open your Ubuntu Software Center (Applications->Ubuntu Software Center) and type miro in the search field. Double click the search result and click the Install button. When installed you can find Miro under Applications->Sound & Video.
Miro in action