[PS1] Metal Gear Solid — but a specific version of a theme

I know this one is crazy. Essentially, I am not looking for the exact MSG1 soundtrack.

Apparently, the theme I am looking for may be "Caverns" (or any other version of it like "Caverns intruder" etc) but actual sound is different than what I found over the net.

What I am talking about can be heard here:
Metal Gear – Angry Video Game Nerd – Cinemassacre.com – YouTube (http://youtu.be/bHyTzPtEAhk?t=2m21s) (Angry Video Game Nerd vid of MGS NES game btw)

Anyhow, as our beloved AVGN explained some details, I noticed the theme. But when googling/youtubing – heck even ffshrine’ing :D, this theme is no where really to be heard.
If you listen carefully, it is much more authentic and cool with that synth-horn stuff -yet I simply can’t seem to find this version.

Or is this theme in an entirely different track and I just overheard it or something?

I noticed somewhat that on certain Let’s Play vids, like the Twin Snakes variant, also had different take. It is likely that this may be due to the respective soundchips (as Gamecube, or better yet the original PSX variant).

Can anybody help me with this one?
If the version as in the AVGN vid does exist, let me know =). Better yet, an upload somewhere would be nice.

Thanks for any help :D!

MGS1 – Introduction Music – YouTube (http://www.youtube.com/watch?v=DVnt4_cRP6k)