What makes me laugh is the tyre with a slug of concrete poured in it being used as a tie down anchor. There about as much use as a tits on a bull.
All they do is add max 3knts to the wind speed that the thing will takeoff on its own. The rest of the time they just sit there stressing the airframe by putting a point load on it and jerking depending how tight the bit of rope is.
Quite a few have managed to get airborne with them still attached.
I have seen a C172 picked up and shifted with 3 of them dangling off it along with a tommy which was not tied down. This was due to a Seaking landing about 100 meters away from them.
Again this something the yanks have more of a clue about with aviation. Most GA parking areas have upside down unbrella ground anchors or sunk eyes in the apron concrete with cables running that you actually tie onto.
AL is used as a low friction metal in alot of designs linked with its low density. Unless it is pre loaded I am not suprised it moved. Its also quite springy under small loads so has a tendency to ping out. Persoanally a half round wooden fence post cut down the middle with a bit of rope linking the 2 sections makes a better chock. Those AL chocks are only good for kidding the refueler on that its chocked so they will start pumping.