I saw a blog post the other day made by astropixie entitled 'understanding the space shuttles' (astropixie is one of the blogs in my blogroll on the right).
It was about a Youtube video uploaded by NASA in December which features a lot of high definition slow motion video taken from the many launch cameras at the shuttle launch site (astropixie links to a lower resolution video, so watch the one below instead).
The video is made by Matt Melis at the Glenn Research Center. One of the best things about the video (apart from the incredible footage) is the fact that Matt and another engineer (Kevin Burke) narrates the video and explains what is going on, mentioning many cool things you might miss if you just watch the video.
The video material is absolutely amazing and the many cameras show the launch from every angle imaginable showing you a lot of cool stuff you didn't know about the launches. The video is composed of footage from three space shuttle missions: STS-114, STS-117, and STS-124.
Do yourself a favour and watch it full screen in HD.
If you liked the video there is another segment, or bonus clips, from the original DVD. They are also narrated by Matt and Kevin but unfortunately they aren't in HD. But the footage is still unbelievable, some of the cameras are more than 30 kilometres away from the launch pad.