It requires the full path to C:\Program Files\AVAST Software\Avast\ashQuick.exe.

Avast in itself doesn’t require a parameter, so it would depend in Orbit downloader needs one.

Personally I wouldn’t restrict what files that Orbit would call ashQuick.exe to scan, scam them all.

As far as P2P clients go if you have the P2P shield enabled and whichever P2P application you are using is checked in the P2P, Expert settings, then you shouldn’t need to have ashQuick.exe scan it.