Youtube thumbnails – there they are

Where do I find and how do I get the thumbnail that my youtube video uses? http://img.youtube.com/vi/<insert-youtube-video-id-here>/0.jpg http://img.youtube.com/vi/<insert-youtube-video-id-here>/1.jpg http://img.youtube.com/vi/<insert-youtube-video-id-here>/2.jpg http://img.youtube.com/vi/<insert-youtube-video-id-here>/3.jpg As easy as that? -Yes! For instance you can have a look at these: http://img.youtube.com/vi/DynNzmdnzqo/0.jpg http://img.youtube.com/vi/DynNzmdnzqo/1.jpg http://img.youtube.com/vi/DynNzmdnzqo/2.jpg http://img.youtube.com/vi/DynNzmdnzqo/3.jpg Thats it thats all!