There are no video chat plugins supplied by Google for Ubuntu. They are availabe just for PC and Mac. Are there any alternatives?
UPDATE: Google has launched official video chat plugin for Linux
http://www.google.com/chat/video
http://gmailblog.blogspot.com/2010/08/use-linux-now-you-can-video-chat-too.html
The default IM application in Ubuntu, Empathy, supports Google Talk voice and video out of the box.
In order to use it, right click on the contact and select either "Audio Call" or "Video Call". Users that have audio capability will have a microphone next to their name in the contact list, and a little webcam if they have video support.
Google also now supports Linux officially in their client, which you can download from here.
Google video can now be used in Linux. gmailblog
You can download it here.
Another popular IM application, pidgin, supports Google Talk voice/video.
It is available from the Ubuntu Software Centre.
I use pidgin for voice chat. You have to enable voice/video plugin of pidgin. The official google voice chat is now available for linux as well
A painless way to install it
In a terminal
My suggestion would be to use gtalk made for chrome os. It can be used in any linux supporting google chrome using this tutorial. http://tutafuta.com/2011/05/25/how-to-use-gtalk-on-linux-or-mac/ you can use this handy trick to do all you can do with google talk, audio/video chatting