You have two problems that I can spot right off the bat.
1. You need to deinterlace your clips to use them on the web. Either do that on each clip in the sequence, or do it upon export.
2. You are exporting 320X240 but showing 480X360 – so someone is increasing the size dramatically, and the quality goes down significantly.
The same general thing happens on YouTube. You send them 320X240 and they show it bigger. But YouTube gives you the choice of seeing the original resolution, which is smaller but much sharper.
I don’t see anywhere on that site that says 320X240, so I would probably start by trying to submit a test at 480X360 with a data rate of about 2048K. The more you feed them the more they have to work with.
Steven
https://www.stevengotz.com