Here is a quick tip on how to get thumbnail images for your desired YouTube video.
YouTube automatically generates up to 3 thumbnail images that are 130 x 97 pixels in dimension and in JPEG format. These thumbnails are accessible in the following URI format:
http://img.youtube.com/vi/videoID/1.jpg
http://img.youtube.com/vi/videoID/2.jpg
http://img.youtube.com/vi/videoID/3.jpg
Using the Power of Ten video as an example, you can get its videoID (BBsOeLcUARw) from the video URL and hence the thumbnail images as follows:
Video URL:
http://www.youtube.com/watch?v=BBsOeLcUARw
Thumbnails:

Powers of Ten - 1 of 3
http://img.youtube.com/vi/BBsOeLcUARw/1.jpg

Powers of Ten - 2 of 3
http://img.youtube.com/vi/BBsOeLcUARw/2.jpg

Powers of Ten - 3 of 3
http://img.youtube.com/vi/BBsOeLcUARw/3.jpg
Bonus:
The bonus is you get a 320 x 240 image with the following (0.jpg):

Powers of Ten - 320x240
http://img.youtube.com/vi/BBsOeLcUARw/0.jpg






![Yíhé Yuán, del Sol [2/2]](http://farm8.staticflickr.com/7018/6598785693_871de66fff_s.jpg)
![Yíhé Yuán, del Sol [1/2]](http://farm8.staticflickr.com/7005/6598770751_501e709ac3_s.jpg)









