Well, it seem to be a purely compression issue, since the output is look great on the video tapes.
One the limitation of today's streaming compression technique are mostly designed for video not for graphic. The graphic element of the video always don't look prefect especially with fast motion. That is the fact.
Have you try,
- another quicktime codec like mp4, or
- increases the compression bit rate, or
- cut down the frame rate, or
- scale down the picture size ?
Those are the way to make your video look better.
Also, you may set the de-noise filter value to 1 or 2 on the color channel, this may help for better use of the limited bandwidth too.
Good Luck,
Antonio Hui