acey, I'm with you about Teresa. Too hammy. Actually there are several of Christi's background people who are pretty hammy (Julie is too but for some reason Teresa bothers me more). It makes me wonder if Christi tells them to ham it up!
My favorites are Brenda from Cathe's workouts and Rhonda and Hope from older Cathes. Hope forever won my heart when she began modifying in the original IMAX. I also like Lauren from KCM workouts although I don't do KCM anymore. I think Lauren has gone on to other things anyway. Patrick G always seems to have great background people who don't "get in the way" of the workout.
Oh and I can't forget Kat Gates Buettner's 2 cats. They are probably the best backgrounders of all!