Well a number of people have full playthroughs and streams of this game on YouTube. Distortion2 has a playthrough over 4 hours, LobosJr over 5. Those are the ones I watched.
There are shorter videos by AlphaBetaGamer and ManlyBadassHero, the former is 50 minutes and the other one was about 2 hours I think? I haven't watched them yet. They apparently reveal all the known secrets and things to find in the game known at the time.