It's really hard to tell what's going on from the video. I suppose everyone is familiar with the flint/steel sparking phenomenon; at least anyone who ever used a lighter should be. There is another phenomenon called a "flash point", the point where a substance will "flash" when heated and exposed to a flame. That could be part of the effect that you are seeing, i.e., the fuel in the fire could be giving off combustible gasses that are just at the right temperature to "flash", but not in sufficient quantities to sustain a flame.