As shown in the video grossly over annealing can melt the case neck. Before reaching that point of melting brass, annealing beyond a point where the targeted annealing area reaches 750 degrees, any degree of consistent neck tension is effectively lost.
When pondering questions such as this always default to applying logic to what ammunition/component manufacturers do. Do they sell you factory ammunition or brass with un-annealed necks? Do they sell you ammunition or brass with randomly annealed necks? Or do they sell you ammunition and brass with necks that are annealed to a fairly consistent degree of hardness?
Annealing is an integral part of making brass. There is a lot of forming involved with making a brass rifle case, and each process will work harden it to some degree. All manufacturers will anneal their brass to reverse that work hardening and provide some degree of consistency to the consumer. They narrow that annealing down to parameters that work with their manufacturing process, none of which would slide towards un-annealed, or over annealed. And none of which are accomplished with a guy sitting there with a drill and a torch looking at the color change.
Annealing for the reloader/handloader boils down to three basic camps. Those that only care about case longevity, those that want that plus a reliably consistent neck tension, and those that LOL at it and consider it unnecessary. All three camps are here on the fire.
There are dozens of ways to anneal and you need to settle on a process that provides a path to your requirements. Is over annealed brass useable? Not to me, because I'm of the camp that wants the consistent neck tension. I suppose lightly to moderately over annealed brass will safely fire, but how accurate will it be? Why create a circumstance outside the parameters that manufacturers provide when it's just to easy to use a system that keeps you within those parameters?
Just my two cents.
