First of all you need Video files of type .mov(Quicktime) , AVI , and .mpg then you can import in to can into Flash MX Pro. Select your video and a box will open up. Select "Embed video in Macromedia Flash Document" for this tutorial. Choose your settings for quality. Less quality means smaller size but reduced picture quality. You may have to juggle this to suit your needs. Choose the width and height of the Flash video by moving the Scale slider.
Synchronise your flash video to the flash frame rate and add audio if you have it.