Well, when I first saw this I thought "wow, did you just KILL OFF A CHARACTER?"
And then I thought about it for a few minutes and realized that the person in question probably doesn't actually die.
I know, that doesn't seem to match up with the ending, but here me out.
1) It's Pokémon. Yes, I know there is some pretty dark stuff in certain areas of Pokémon, and that there have been characters like Cyrus in Pokémon the Series or Lysandre in the games, and I know that there have been more character deaths referenced in the more recent movies, but in general Pokémon tends to tread cautiously in the area of killing off characters.
2) This character has the Arc Phone. Which, by the way, I think was probably created by Arceus. That, and everything else in the Pokémon world, but you know what I mean. I'm guessing that Arceus has some sort of plan for the player character and has given the player this bizarre futuristic devise to aid him/her in his/her quest (not exactly time traveling, but still miraculous), and that the person in this video is PROBABLY the player character. As for a VHS Camera, it's all the Arc Phone. And he refers to the device in question as a "strange device," so this is NOT the technology produced by this era. He reels off the information about times in a monotone voice (as if he's reading off a script... or a phone screen) and corrects himself immediately when the minute changes, he fears that the device won't do it's job... it's clear that this technology is nothing his generation is familiar with. So at this point he's probably still a novice. Which leads to
3) This is a game where players can be attacked by wild Pokémon. Which makes sense when you consider this video. HOWEVER, no sensible adventurer is going out into the wilderness without Pokémon companions for protection against attacks. Not to mention if you faint in the games (yes, faint, because apparently you're a second-rate Pokémon now), which adds to the unlikeliness that this person is dead. The thing is, we never actually see anything but the strange Pokémon's leg. So perhaps the trainer was pinned to the ground. Or perhaps he just dropped the phone and ran. In either case, he's gonna be fine. He's just going to release a Pokémon from its Pokeball. He has probably ALREADY released a Pokémon from its Pokeball. He probably has a ride Pokémon within hearing range. In fact, he doesn't even NEED to release a Pokémon from its Pokeball; he just needs to throw an EMPTY Pokeball at the Pokémon and fall back when the Pokémon becomes encapsulated. And speaking of tactics
4) The player character is a smart cookie. He'll be fine.
5) We don't hear any death screams. He says "gwaa!", we see the Pokémon's face just STANDING there for several frames, just STANDING there passively, the screen flickers out for SEVERAL seconds, and then we see the phone lying near the Pokémon's feet, which are ALSO just standing there passively. So this Pokémon isn't actually attacking him.
6) The phone survives. Which means someone came back for the phone. After a certain amount of time the phone would have stopped functioning because of the cold. Assuming it didn't get trampled by the aforementioned Pokémon. Also, if someone came (back) for the phone, that person would have to get past the Pokémon in question.
7) It's eyes are closed. If it's eyes were open, this video would honestly be much more menacing. You don't walk up to a human you want to eat and then CLOSE YOUR EYES and STAND THERE. That's an easy way to get hit on the nose by a Heavy Ball. Or just sprayed with pepper juice. (Tamto spray?) This thing is not angry, this thing is not hungry, and this thing is most certainly not a killer.
8) The video footage was already horrible. The fact that it flickered out proves nothing. It is not sufficient evidence to justify the claim of an off-screen death.
9) The Arcanine line has very close ties to humans. Possibly the weakest evidence since we don't know much about this species.
10) The player character literally screams when he hears footsteps. He probably just dropped the phone and ran. (Perhaps I need to remove evidence 4?) In addition, he himself said that the area had a "mysterious air." By that point he had probably weirded himself out, and seeing the Pokémon's face up close did him in. He simply bolted. (But he came back later for the Arc Phone.)
11) The adorable Pokémon turns his way, but it doesn't cry out in distress. The mother isn't going to be rushing into the cave high on adrenalin in a maternal protective frenzy. Also, see evidence 7.
12) Someone had to get this video footage off of the Arc phone. Someone who knows how to... well, how WOULD you save this footage off the Arc Phone itself? Certainly not as an MP3 file on a harddrive.
Also, did I mention this is Pokémon?
One more thing. LEGENDS Arceus has received the customary E rating, so I would honestly be surprised if this character died because of the rating of the game itself. Still, I was a little shocked by the way this video builds up the suspense and by the way it ended. Not something I expected from Pokémon. Fortunately I didn't see the face clearly during my first watch-through or I would have had a panic attack.
Also, this is basically the Glimwood Tangle camera event, only as a short video with a more dedicated plot.