Are there any videos out there that show rhythmic backup fiddle (YouTube or "paid for" website)?
Stuff like this, especially the intro ... Cluck Old Hen - BEECHARMER
And that video leads (at least for me) to a lot more on the same topic.
I looked through some old dvds, turns out I have a copy of that one. Couldn't get the fancy chops up to speed, but I will go over it again.
I wouldn't call what that fiddler is doing is chopping. He's doing rhythmic bowing over changing double stops, and really only in the beginning. How do you learn to do that? Someone here has posted a nice"fingerboard map" of the various double stops to make chords. In various keys. Learn some nice shuffles that you can vary. Learn the double stops that correspond to the chords you need and practice, practice practice. Then realize that you don't have to play much in the way of backup fiddle in a group the size of that video 
