Honestly, I wouldn't worry about them or try to fight them. Every tank ends up with detritus worms eventually, and they're actually beneficial.
From photo and video, no way to tell exactly what we're looking at, be it nematodes or detritus worms. What I can tell you is it's not planaria(a concern) and it's not rhabdocoela(not a concern).
If you're dead set on dealing with them, do it after you flood the tank and dose Fenbendazole.