Some essential Google Video search tips:

• When you search Google Video, the triangle icon on the screen shots indicate those items you can play back for free.
• To limit your search to playable items, use the playable directive, e.g. singers playable:true.
• Choose between the grid and list views by clicking those options on grey line just below the Google Video logo. The list view provides listing details for each match.
• Remember that a Macromedia flash player must be installed in order to play back videos in your browser.

Thanks to Jason Tucker.