Well the text looks much better but the footage doesn't look better at all.
Do you know if it was shot progressive, can you see interlacing in the source footage?
To make a great improvement with this footage you are really going to have a to get a dedicated transcoding application, FCP is a great NLE but it is not a great transcoder.
Ideally you should be exporting out of FCP straight to whatever is your FLV transcoder avoiding any intermediate steps, like going to H.264 for example.
Have a go with ffmpegx it's not the easiest to use but it's free. If you want anything better look at Episode.
http://homepage.mac.com/major4/
I'd recommend you export out of FCP as a reference movie, not self contained and take that into your transcoder.
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Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!
