The video features multiple explosions, but perhaps the coolest looking one involves a pair of mannequins (Doris and Frank, if you want to become attached to them before you watch them get blown to unrecognizable bits). The guys wrap them up in "shock tube," which, as Daniel Grunchy points out, facilitates a "dust explosion, which travels down the tube at about 2,000 meters per second." This activates a detonator, which sets off a "det cord," which is what explodes and makes things go boom.
Sure enough, when the explosion happens, it just looks like an instant fiery inferno. As Gavin Free pointed out, it takes place over a span of 0.02 seconds. As such, the real magic comes when the video is slowed down. At super slow motion speeds, you can actually see the charge travel through the tubes, wrap around Doris' body and blow her up, which activates a second explosion that shoots through Frank's torso.
I'd feel irresponsible at this point if I didn't note that you shouldn't try this at home, because you're not as prepared or qualified as The Slow Mo guys are. From their video description, "It was performed safely under the supervision of explosives experts. Additionally, Dan has training as an EOD in the British Army."
Explosions are better watched than explained, so check out the video above, and let us know in the comments which of the booms in this video is your favorite.
Featured image: The Slo Mo Guys