Quote: "it depends, what file extensions are they?"
they are .mdl files
Quote: "And how, may I ask, could this benefit everyone?
Because, surely, you cannot use the counterstrike weapons in ANY kind of distributable product because that would breach copywrite."
If you checked the website i gave you, you can see that counter-strike does not make these models, the players do, and if you ask them if you can use them in a distributable product, like I did with the game I'm making, then you can download them, which you could have done in the first place, then use them in your game, that is why it is a very cool site.