Hi Burr, I suppose those are probably knot locations being displayed on the curve.

But notice in the video that with the 2 kinds of points displayed at the same time he only ever drags on a single point to do the edit? (or at least in that particular spot of the video).

Moving just 1 point is fine for many situations, but it can also be useful to grab a whole set of control points with a window select and move all of them in one operation.

But doing multiple selection of both kinds of points (both "on curve" points as well as control polygon points) is going to be problematic because each kind of point needs to do a different kind of edit to the curve, you can't do both types of editing at the same time.

Maybe they do something arbitrary like just ignore edit points if there are also control points selected or something like that - but it tends to be far better to avoid having ambiguous situations in the first place.

- Michael