fukkery starts at 0:28....
Who's at fault brehs???
I've often dealt with tailgaters shyt is nerve wracking and fukking annoying...

but i've never break checked...
Both are at fault.
The driver in front who hit the brakes didn't have a reason to brake. The car ahead of it was a far off and wasn't braking and nothing was in the lane that would require braking. The driver could be charged with reckless driving. The driver who crashed can also be charged with following too closely.
What to do? Well, think of every car around you having a car camera that is recording and there's a judge in one of those cars. What would you do to "not" get a ticket?
When you have a tailgater, use your turn signal and try to get in another lane safely (if you are in a multi-lane highway). Unless it's a road rage case where he's looking to tailgate you, you will usually see that car speed off. What else to do if you are stuck in your travel lane? One thing is to ride the brake pedal, or slightly depress it so the brake light is activated, but you aren't going any slower. This works sometimes. Sometimes not. Maintain a safe distance between yourself and the car ahead of you.
Braking hard to avenge the tailgater can result in you getting charged with reckless driving or more if someone gets injured or killed from your stunt. Why? Let's say the same scenario happens, but instead of the tailgater wiping out, he hits you from behind. There are going to tire marks created on the highway by your vehicle, and the ones behind you. The police will investigate the accident and if the situation requires an special auto accident investigator to show up, they are going to take photos of track marks, vehicle damage, and everything else. He or she will be able to pin the cause of the accident to the brake checker.