bitrate vs filesize, what the hell?

[Phat J]

hi, i have a svcd music video, i had to re-encode it from pal to ntsc, i just opened it in tmpgenc and loaded the svcd ntsc profile, changed the bitrate to 2520 kbs Constant Quality and Motion Search Prescision to High Quality, left everything else, then encoded it.
the video is 5 mins 36 sec long, and the file came out to only 66.8mb! im thinking it should be around 100mb.
i checked the video bitrate and it was 2520 kbs, and the audio bitrate is 224 kbs, the video looks fine for quality, but just how does this make sense? such a high bitrate in a small size file? i didnt choose vbr unless it does it automatically?

[Martyn1980]

Constant Quality is a form of VBR, just a quicker more unpredictable version of it, you need to select CBR, but if the video is fine, then stay with CQ as it does produce good results at small filesizes sometimes.

[Phat J]

ohh now ic, thanx for clearing that up