Good point. We do our best to educate users with intro rowing videos that can be found on the touchscreen. Any any time the resistance is at a high level, we use little animations that show proper form and technique.
There are two major rowing postures you'll find people tend to use, hips rotated forward and hips back (spine slightly arched forward/convex). Neither is really wrong but for high resistance you need to be in the hips forward position (back slightly concave) as is the technique for weight lifting in the seated row. IME most people don't actually comprehend which position they're in but using the wrong one can be catastrophic. You typically have to spend a few hours with someone ensuring they stay in the correct orientation before they really get it.