I really try to avoid watching playthroughs if I have any interest in a game and haven't played it. The few exeptions are...
Until Dawn: watched Easy Allies play it because they are fun to watch and I had no money to ever buy the game.
Brothers: I wanted to see what it was about from a development point of view but I didn't have time to play it myself.
Halo 5: I knew I wouldn't be getting an Xbox One for years.
Sunset Overdrive: same as Halo 5.
Ryse: same as Halo 5.
Until Dawn: watched Easy Allies play it because they are fun to watch and I had no money to ever buy the game.
Brothers: I wanted to see what it was about from a development point of view but I didn't have time to play it myself.
Halo 5: I knew I wouldn't be getting an Xbox One for years.
Sunset Overdrive: same as Halo 5.
Ryse: same as Halo 5.