facebook hd video bitrate

What is a good bitrate to use for Youtube HD videos?
OK I’ll tell you what I’m doing and try to let you know some of the details of the files.
I’m using Sony Vegas MSP Pro 9, I’m using the raw footage from a canon sd960 @ 1280×720 it says they are H.264 files. I render them to Sony AVC (mp4) @ 1280×720 and bump up the bitrate from 500,000 to 4,000,000.
I just did a video for motocross jumps and it turned out with motion flickering. the raw footage has none at all(I put it on Facebook). My videos are 2 minutes on average and 6 minutes at the most. This is a question of curiosity really not a real big problem. I just thought I’d drop the question here. Playing with the setting takes up a lot of time.
My computer has an Intel q9550 quad core OC-ed to 3.3GHz with 4 gigs of memory @ 1066MHz So I’m not worried about my computer being too weak.
the problem is that your source is MP4 to begin with, it has high compression and adding bits when re-encoding will only make the file larger, all of the compression artifacts will still be there, regardless of the resolution captured. since you are dealing with high motion video, it would be best just to post the raw capture to youtube, but if you must reauthor, do not change the bitrate, but be aware that any recompressing, even at the same bitrate, will cause compression artifacts.
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