Works (for now?) as of Oct 07 2012 Rated 5 out of 5 stars

No complaints at all, I tried to clear out my DL history, no problem and Browser hist was left untouched
3 options; Clear DLs instantly, - on exit or - on demand
Let's hope FF doesn't F this one up again

This review is for a previous version of the add-on (1.2.1-signed.1-signed).