Hat tip to Civil Warriors for this awesome video of a film that is held at the Library of Congress, but was made available online via the Smithsonian. I have heard a recording of the Rebel Yell before, but this is by far the best, as you can see the actual veterans doing the yell. Though the audio quality is a bit grainy, this video represents the power of digital history in making a unique piece of American history available to the world. Check it out, as I am sure it will send a shiver up your spine.
You should also check out this interesting article on video and audio recordings of veterans.