MF6 - why would AVI export have black bars on left & right?

[DudeBoyz]

DMF 6 with HD powerpack installed.

When I export a multi-trimmed vid (or any vid I guess) to AVI, either the built in DivX 5.1.1 or x264, the tv episodes I recorded from my tv signal (like Deadliest Catch on Discovery Channel), end up with black bars on the left and right, sort of like Letterbox that is often on DVD movies on the top and bottom, only on the sides.

If I export the exact same file to MPEG, it does not have that black space on the left and right sides.

I have tried the "TV Safe" setting from 10 to 0 but that seems to have no effect. I record at 720x480 and do not have widescreen tv or HD cable, just regular basic cable stuff. I'd like to get it to export without those bars on the left and right so that it does play a true 720 pixels wide, but cannot seem to be able to. So, that's why I'm asking for help.

I'd appreciate any helpful replies. Thank you.

[Black Lab]

If you do not have widescreen or HD tv then the video is being recorded in 4:3 ratio, but it sounds like your project settings are for 16:9. So you are putting the 4:3 video in a 16:9 project, filling in the sides with the bars.