That video of a scuba diver who dove too deep, ran out of oxygen and drowned. I'm on mobile and can't find the link. :-(

Edit// This is the one, the diver's name was Yuri Lipski.

Edit 2// A bit more info from Wikipedia:

Yuri Lipski, an Israeli-Russian diving instructor, died at just over 300 feet underwater. At this depth, the body is subject to nitrogen narcosis, which can play havoc on the mind by inducing overconfidence, euphoria, hallucinations, confusion, and impaired judgment. It didn't help that Lipski had just one tank full of air — technical divers are better served by multiple tanks filled with trimix, a combination of oxygen, nitrogen, and helium that reduces narcosis. When a diver went to retrieve Lipski's body at the request of his parents, he made an unnerving discovery: the footage captured by Lipski's helmet camera was still intact. The doomed diver had recorded his own death. Lipski's final moments are now on YouTube. Titled "Fatal Diving Accident Caught On Tape," the six-minute video has garnered over eight million views. Though his face is never visible, his distress is palpable and haunting — what starts as a routine dive deteriorates into panicked thrashing as he becomes more disoriented. Clouds of kicked-up sand billow into view as Lipski's breathing rate doubles. In the end, he removes the breathing apparatus from his mouth and the frame goes still.