It does sound like the freehub body banging. I get it very occasionally (one a month maybe) it's the pawls I think - nothing to worry about. If it's coming from the BB: something to worry about.
I've taken the freehub off, adjusted each leaf spring (which are in the hub body) and put it back together, hasn't helped. Starting to think it might be the bearings in the hub now, so have bought new ones to put in and see if that helps
It does sound like the freehub body banging. I get it very occasionally (one a month maybe) it's the pawls I think - nothing to worry about. If it's coming from the BB: something to worry about.