If you're linking to a .mov file, then a link is all you need. But, if you want to have part of your webpage an actual movie, then you need to click on the cell (I'm assuming you cut up your jpeg which made a table out of it so you could replace the area with the movie, right?)... and drag in the Quicktime icon from the tools palette. Then, just specify the size and link to the qt file in the Inspector palette and you're done.
I did
http://www.donfriesen.com
the high-bandwidth version all in flash, but if you click on the video link, a separate window pops up with video clips. Just view that source and you'll see how it's placed in the file.
If you're just using a huge image map, then you can only just link to the Quicktime file externally unless you use javascript.