FLV File Size: 720x480 same as 320x240?

I’m a bit confused…

If I export to FLV video from Final Cut Pro, it doesn’t seem to matter whether I output to a file whose dimensions are 720x240 or 320x240, the file sizes seem to be the same. (6MB for a one minute clip exported in Flash 7 high quality).

What gives?

Shouldn’t I get a smaller file size in the flv if I cut down the dimensions of the video? I’m trying to keep the file size down for employment on the web.