This is from my talk, How to Shoot, Edit, and Publish Web Video, at MAX 2007. For more step-by-step tutorials purchase my book, Producing Flash CS3 Video.
Importing video into Flash Professional CS3 is eezee peezee.

First, download the example file: video_wizard.zip.
Unzip this archive and then open wizard-example.fla in Flash Professional CS3.
Select File > Import > Import [...]