It can only work up to a limiting frequency. It’s probably in the visible spectrum or in near ultra-violet (that’s how material go). But since it’s a video, I won’t go check it.

Looks to me like only the tentacles are glowy, and the body and eyes are just reflecting the camera’s light.

old pla which snapped all the time because it wss so brittle

That’s what extremely wet PLA looks like.