Millennial anti-theft device

[JTG]

It's easier to see in a stabilized version of the gif, but you can see a reflection of both the fire (starting at 0.25 seconds) and the first flare-up (at 0.91 seconds) in funnel-man's sunglasses well before the flame flashes over to the shop-vac blower (1.2-1.3 seconds), and the flame front is clearly moving to the left, towards the funnel outlet. The fire on the shop vac seen afterwards is from funnel-man jerking the tube away from the flare (1.5-1.7 seconds), thus emptying the contents onto the vac and his friend. All evidence points to an active fire in the fire pit as the point of ignition.