Here’s an answer from Rob Lohman at a different location:
Greg: the project settings should be widescreen 16:9 in PAL or
NTSC. Don’t change that!
When exporting QuickTime go to custom and then video tab.
Make sure frame size is set to custom frame size and set the
vertical to normal (which will be 480 pixels for NTSC or 576 for
PAL) or a lower value (which you usually want if you want to
put it up on the web!), usually 50%.
Then use then multiply the horizontal resolution (720 for both
PAL & NTSC) with the pixel aspect ratio number in the project
settings (which is 1.2121 for NTSC and 1.4568 for PAL 16:9).
This should be either 872 (NTSC) or 1048 (PAL). If you are using
a lower resolution take the same percentage out of the horizontal
resolution as well (usually again 50%).
Make sure the pixel aspect ratio on this screen is set to 1.0
This should get you a widescreen movie.
Edward Troxel
