This one on K2 was really interesting. It goes in-depth on why K2 is so much more dangerous than Everest and the many failures of the people attempting to be the first to make it to the top.
Do you speak German or Dutch? It‘s not a documentary, but Toine Heijmans wrote a spectacular book on mountaineering called Zuurstofschuld. There‘s only a German translation though so far. I read the thing cover-to-cover in three days, best read I‘ve had in a while.
Not exactly what you're looking for, but "Scary Interesting" on youtube has some good mountaineering gone wrong stories. They're typically 10-20 minutes long.