This abuses a glitch in how the game handles holding down one of the command keys in combat - your character spazzes out, draining a lot of stamina and messing up your character's animations. I used this as a kid to win the demon mirror fight - if you dodge in this way, then you let go of the key after the spazzing has begun, then your dodging animation will not end properly and you can just stand still and regain all your stamina while invincible.
This isn't really the fastest possible softlock for Alone in the Dark, but it is if you're using TAS timing (i.e. end timing at last input). This is something that happens whenever objects spend too long out-of-bounds. The lamp is gotten out of bounds by lagging the game at the right time. You can see it wrapping around the plane a few times before Emily stops moving.
After this crash happens you need to reboot the PSX. Is that a softlock or something else? I don't know which level is the earliest one where this can happen. It's very rare and random.