This is a video of a group of skydivers losing altitude awareness and narrowly avoiding being turned into pancakes on the side of a mountain. Apparently the group was the second to exit and nobody noticed the drop was at the wrong place until it was almost too late. All their safety gear (AADs, audible altimeters, etc.) was set for ground level and nobody noticed there was a mountain where there wasn't supposed to be. Anyways, nobody dies, but apparently this is a famous video in the skydiving community as a reminder to spot your jump location and make sure there aren't mountains where you don't expect there to be mountains. Seems kind of obvious, but apparently not.
Keep going for the full video.
And a video of two skydivers being saved by their AAD (automatic activation device) after forgetting to pull their chutes: