prepare .mp4 video for flash video

I captured footage with my Sony HD AVCHD camcorder, which generated .m2t files. I then brought those into Sony Vegas Movie Studio Platinum 8 and rendered the clip as a Main Concept AAC/AVC (.mp4). So now I have a .mp4 video file that I want to insert into my webpage using Flash Professional CS3 and Dreamweaver CS3.

Can someone tell me the steps to go through starting with my .mp4 file to get the necessary flash video files for upload on my host ftp.

When I try to use the Flash Encoder it plays audio but the video is blank. I have figured out how to go from a .mov file and encode in the Flash Encoder to get a .flv for my webpage.

The reason why I am trying to do the .mp4 is because I understand rendering to that type of file will yield the best video quality. I may be wrong on that and if I am please correct me. I want to render my clip to a format in Sony Vegas that will eventually lead to the best video quality once in encode to Flash.

Thanks in advance for your help. I have spent hours trying to figure this out with no luck. Just the audio with a blank video screen is all I have been able to get.