Encoding for faster streaming and MP4Box ?

[Miata]

I'm running XP, using sony vegas pro 8. The headache of the day: I'm uploading vids to a private forum but either the quality is awful or it takes forever (20 or more minutes) to load. MP4 is my format of choice, 640 x 480 or thereabouts and another user uploads mp4 and her vids immediately begin playing... so I don't know what I'm doing wrong and she's been away for some time so I can't ask her.
I have read about mp4box (yamb?) and mp4 fast start? And I've also read that camtasia works well but I don't know anything about those programs or where to place the codecs or import the programs, how to use them, etc. - I'm willing to learn.
If anyone here can point me in the right direction, I'd appreciate it.

[Baldrick]

Just load the mp4 in mp4 fast start and make a new mp4 that should start playing directly using flash.

[Miata]

Thanks. I'll definitely give this a try, sounds simple enough. Again, thank you so much.