I believe youtube has a 2GB file limit. But as far as file size. How long is the video? The settings I use gave me about 260mb for a 5 minute HD video. I'm using sony vegas, but the settings should work for whatever you're using.
In the custom settings this is what I have set:
Video Format: AVC (comes out as a .mp4 file)
Frame Size: High Definition (1280x720)
Profile: Baseline
Entropy coding: CAVLC
Frame rate: 29.970 (NTSC)
Field order: None
Pixel aspect ratio: 1.000
Bit rate (bps): 6,000,000
Here's how it came out. No real editing, just playing around with some footage from one day this season. Watch in 720p for best picture. And this file was only ~260mb