Movie for iWeb showing up in 4:3 instead of 16:9

[tac22]

So i finally found a way to compress my movie, to make it small enough. And while when i play it through the quicktime player it is 16:9, when i put it on iWeb it gets smooshed into a 4:3, so its also slightly distorted, and i can't just resize it, that just makes it bigger or smaller. Help! if you need more info just ask