The Mantis simulator rig in the video above is one of several shown here in the HG WIKI:
I believe the HG Simulator concept is extremely valuable in teaching beginners to fly HG. You can let the student get relaxed and comfortable, and then take all the time needed to teach (and correct if necessary) all the right control moves. You can also teach them how to go from prone to upright, without the glider rolling and pitching all over the sky. The transition from launching to prone can also be practiced and smoothed out. The last thing any beginner needs is trying to land with a lot of unwanted pitching and rolling on approach. There is a fairly complete "ground school" briefing in the WIKI that goes with the drawing, for use with any HG Simulator.
Seems like the Mantis instructor has an unwarranted fear that his students will confuse roll with yaw, and he immediately transfers this needless concern to the student. IMHO, that anti-yaw device at the rear is beyond useless; it is counter-productive. Most students have no concept of yaw, and he is "fixing" a problem that is not real. Bringing up that "yaw confusion" to a new student is like telling somebody "Don't think BLUE." The immediate human response is to think BLUE, as a result. I see no real need for the "anti-yaw" device on the Mantis. On the rare occasions that confusion may happen, it is easy to correct. N.B. If the Mantis rig was left at a lower height at first, it would be easier to mount the glider on the Heim connection, but hey, what do I know?
The last Simulator in the WIKI here is simply a Heim connection, mounted on a common engine hoist, although the one shown there is a welded framework that duplicates an engine hoist. If you do use an old engine hoist, though, clean it very well first. Those things are always very oily/greasy. I'd suggest covering the arm and legs of the engine hoist with oil-proof plastic coverings, to keep the glider clean.
For any use of the HG Simulators, take care that the glider (with student) is trimmed for "level flight" when the student flies "hands off."
My $.02 worth.