The Collapse Cross Tangent command allows you to set the cross tangent values of your XirusCAD object at the selected point(s) to 0.
You can call the Collapse Cross Tangent command from the XirusCAD menu, from the XirusCAD Toolbar or from the command line. Select the points on your XirusCAD surface. The cross tangent of these points will be collapsed. This means that the cross tangent values at those points will be set to 0.
In the video, the Collapse Cross Tangent command is found under a different XirusCAD menu item.