Dynamic crossings are built-in crossing types. Crossing types that can be adjusted inside the tool. For instance the width, corner radius, resolution, sidewalks. Currenty supported are X and T crossings and roundabouts, more options like Y crossings and cul de sac will follow in v3.x.
New tutorials will follow, below is the provional beta video. Although it is not 100% up to day it can still be used as a reference