If you watch the video no one really screwed up epicly or did anything outside their class role. Barb/monk were attempting to lock in the mobs at the stairs, frozen nodes spawned behind them and this basically forced them into a fight or flight situation. They really can't run since the ideal position to engage is on those stairs, and a bunch of stray ranged mobs puts their WD/DH at risk.
The monk made a questionable move attacking into the pack that deeply but I feel as though that was a miscommunication issue. The barb followed up by doing his job trying to save the monk since a barb has a much better chance to survive that situation than a monk. I imagine after leaping in WotB faded and CC locked the barb or he wasn't able to revenge spam enough targets due to ranged mobs. I've seen multiple HC barb streamers do this if forced to since they are basically the only shot a trapped person has at surviving. I probably wouldn't pull this stunt in a pub game but if I was playing with friends I would do the exact same thing on my barb whether the trapped person had a vagina or not.
I personally think the barb was pretty relaxed about the death since he died a pretty epic HC death. Most people lose their HC character to fire, disconnects, retarded affixes, or stupidity while this guy earned e-peen points for life saving his buddies in a blaze of fried barbarian glory.