Wow… and actual volcano explosion shock wave. Insane. Hey! We can do math on this!
The explosion happens at 0:12 seconds in, and the shock wave hits at 0:25 seconds. 13 seconds for the shock wave to hit the boat.
The speed of sound at sea level is 331.5 m/s (741.5 mph)
Velocity = Distance / Time
Distance = Velocity x Time
Distance = 331.5 m/s x 13 seconds: = 4,309.5 meters
Ok.. so now we know the distance to the volcano… we can assume:
Density of the air at sea level = 1.224 kg/m^3
Speed of sound = 331.5 m/s as above
r = 4,309.5 meters from math….
If we had a calibrated microphone on the camera we could use the following equation from the paper "Generation and propagation of infrasonic airwaves from volcanic explosions" to calculate the pressure in the volcano at the moment of explosion.
My raw notes for posterity.