[Update: Okay folks, the sequel is out now, so go check that out in the case you even remotely liked this!:)]
Snake is making his way to the latest Metal Gear in production.
The Major is a purely fictional character, kind of a mixup between Colonel Campbell and Major Zero.
The movie itself is rather short, because the sounds take up a lot of the filesize.
I would recommend playing Snake Eater first or you will propably miss most of the movie.
Any kind of constructive critisism is welcome, so that I can improve my work in the future.
Since so many people have pointed it out, I'm going to say it here: The name of Snake is in MGS3 indeed Naked Snake, not Solid Snake.But, the main character in this movie is SOLID SNAKE.And, if you take a closer look, the events are situated on a different continent:Africa, not USSR/Russia.
The whole series is going to be a mix of all three games.I hope this clears things out a bit!:)