Gmail team has rolled out some High Quality Video chat for its user.It allows you to view bigger video chat window with high resolution.
In order to use this feature you need to activate through Gmail Labs.To activate it :-
First sign in to your Gmail account,
Then click on Setting and then on Lab tab Or just use THIS LINK,
Now scroll down an you will find a lab feature Video chat enhancements,Just enable it.
The higher resolution video uses a new playback mechanism which enables widescreen VGA and frees up valuable resources on your computer. For it to work, both you and the person you’re chatting with will need to have the lab turned on.
If in future you want to roll back then in that case just Disable that Lab