These videos are a really useful tool. They can be of great help in your quest to improve your  English. Here's only a few. There are more than 100!

http://www.youtube.com/watch?v=uWHhpb8NWcI
http://www.youtube.com/watch?v=ve981fbBY0g&feature=relmfu
http://www.youtube.com/watch?v=WAJ2ffma91Q
http://www.youtube.com/watch?v=886hLlkwipI&feature=relmfu