Iain: I think it could be either Nocturne of Blair Witch.
That small video is very similar to the intro on Nocturne with the way the Police are dressed on the Nocturne intro, same kind of era with the Military uniforms, it has a very similar vibe to it.
Then you have Blair Witch, this was done by Human Head Studios who also done RUNE which is available on GOG already
Nocturne and The Blair Witch Project Volume I : Rustin Parr were developed by Terminal Reality.
Human Head studios developed TBWPV II : The Legend of Coffin Rock.
Then another studio developed Part 3.
And yes, there's also a device in Rustin Parr that sounds like the sound you hear on this video that's on the First Post.
Then again, it doesn't sound QUITE the same... So i guess STALKER is the game...