I still have F100 clients who forbid streaming audio on their intranets, let alone video, and Flash is for them a definite no-no. So do not underestimate the bandwidth issues!
Video - and the other rich media - should only be used where there is a learning objective best served by it, and then only used sparingly. There is nothing worse for a learner than to have to sit through hours of gratuitous talking-head video. But if used to illustrate a point, behavior, or process, well-crafted bits of video can be very powerful.
The bandwidth demanded by your video will depend on so many factors, including the size of the window you play it in, the frame rate, the compression format you use and so on. Typically, for streaming video to a 400x200 window at 20 frames a second, you need about 360kbps of bandwidth per simultaneous user. Higher res or higher frame rate, and it can shoot up exponentially. Use a good compression algorithm like Flash MX04, and it can drop. Get your IT people involved early, define a bandwidth budget, and fit your video chunks into it.