Right, I've played the NTSC version (via an emulator, and used the cheats), and done exactly what the bloke in that video did to get 63/64 kills, and I have managed to find (and kill) the enemy that that bloke didn't find. That's the good news.
The bad news is, no matter what I try, I can only find 62 enemies on my own. I've done EVERYTHING that he did, but whereas he gets 63/64 kills, I get 61/64. Or if I kill the missing enemy, then I get 62/64.
First, the missing enemy; do everything exactly how the bloke in the video does it, but when you kill the final cyborg (at 25:57), do not go into the teleporter. Instead, turn around, go back though the room with the two unconscious/dead cyborgs in the cabinets, and DON'T go through the teleporter, instead go through the door that leads into the ship's corridor. Go along the corridor towards the part with the stage, and the missing enemy (a flying drone) will attack you, it's hiding near the wall. If the bloke who did the video had done this, then he'd have gotten 64/64 kills.
But even though I've done everything he's done, and killed everything that he has, the game shows me as missing two kills (or three, if I don't kill that last flying drone). I have no idea what's causing that. Using the cheats, including the on-screen display of how many kills you have at that moment, I can confirm that if a flying drone hits you and deliberately explodes, then that IS counted as a kill for you, so whether you :pottymouth: and destroy a flying drone, or whether it hits you and explodes of it's own choice, either way you are credited with 'killing' it.
I've gone through the video, and written down every kill in that video. Here's the results:
15.Flying (low) Drone5:02
17.Flying (low) Drone5:18
19.Flying (low) Drone5:47
29.Flying (low) Drone9:46
39.Flying (low) Drone15:42
41.Flying (low) Drone16:42
46.Ceiling Turret (behind Cyborg)19:21
('Enemy' just means an enemy that's alive, usually a lizard thing).
So unless I've missed two kills, or he killed two with one :pottymouth: a couple of times (which doesn't explain why I can't see the enemies in my playthroughs) then there's something very strange going on. Any ideas?
Edit: It's just occured to me that I've played the game on normal, and maybe he's played it on hard. That doesn't explain why he'd be credited for two kills that don't seem to take place (from looking at the video), but if it is a bug, then perhaps it only occurs on hard mode. I wish he'd said what skill level he was playing on, and if his version of the game was PAL or NTSC.