Must've been EOD or a Ranger or such - no imagination - just blow it in place and make a loud boom for the giggles.
When we were cutting up a small sunken freighter just outside the main channel area in Gatun Lake, we'd place the main cutting charges and then back off, toss a small short-fused 1/8 lb 'kicker' to chase the bass towards our main charge, and then detonate the main charges. Then we'd motor around and police up the floating Peacock Bass to be used in our nightly
saviche meal. Some good dining courtesy of some good demo men.
Those guys in the video were rank amateurs.
Richard