I rarely cringe at videos. This one got me.
A top commenter on the video described this dish as follows.
This Japanese delicacy known as odori-don or “dancing squid rice bowl” is a variation on traditional squid sashimi and uses soy sauce to create the disturbing illusion of bringing a dead squid back to life.
Apparently the sodium in the soy causes neurons to fire, making the muscles twitch. The squid was completely motionless before the sauce was poured on and was definitely “dead at the time of serving”.