Another video on technique, how you should have your rower set up, and the reasons behind setting it up the way that we do. "Drag factor" is a value specific to Concept 2 rowers, but the video explains what happens when you increase the damper on the rower and why you want to row with it at a lower value.
These concepts also apply to rowers other than Concept 2, although how you adjust the resistance may change.
