We do this a fair amount after video analysis. We also do peer coaching so people have a chance to look at/be looked at by their seatmate and those in front and behind of them. I find sometimes having others verbalize what you're trying to do may connect in a different way.
I think one of the biggest things is to make sure they understand what they are supposed to get out of the drill as you'd be surprised at how many people walk through drills without connecting the point of it to how they paddle. Otherwise you'll get a whole lot of "it was good"s.