So, what is the advantage of using Fraps for the capture, rather then just convert from an ahf?
Actually, converting via the AHF is better. IIRC in the AHF, the outputted .avi files are uncompressed and have no codec attached to them. Recording with fraps captures video in a Fraps codec, so there is some compression going on.
Fraps may be easier to record and set up. That's the only advantage I can think of.