If the video is blown up to full screen, you can see two tiny flashes down by the diffuser. First on the left and then just before take off, on the right. Is this what we are talking about here. I would have thought it might have been a more constant and even flow of “warming” gasses as the wheel is turning for even distribution of heat, not a pinpoint explosion or the like.
hmmm… curiouser and curiouser…