Clearly the squid is reacting to the soy sauce. What I meant is that when the person first pours the soy sauce over the front of the squid, the back tentacles start moving even though they don't appear to have come into contact with the sauce at all. I guess we'll have to agree to disagree on what "random" movements look like, and I'm not really sure what sort of reaction you expect it to have from being pushed around a little bit or why you'd expect a half dead squid to have boundless energy.
Here's a better clip. There's no doubt that one was still alive.
I don't expect it to have boundless energy. THe squid wasn't moving at all in the beggining. If it is indeed alive and flipped out from the soy sauce I expect a push that isn't exactly gentle, he moved the squid with it, to cause some type of reaction from the squid, like say even attempt to grab the hand. Also yes I expect a living squid, even half dead to either not be able to move quickly at all or to move around for more than 10 seconds quickly if the soy sauce is indeed just bothering it and not causing the actual movement. Maybe it is alive, but I don't think its movements indicate that if salt does cause dead animals to move around randomly because the movement is just random.
The squid in the other video does seem alive though as it actually looked like it just flipped out when the sauce was poured on it.