The mixture at the tip of the needle was lit and is burning, which is understandable. What I don't understand though is why the flame doesn't travel up the needle and into the syringe.
Normally burning process is restricted by oxygen supply (which in order is restricted by products of burning, like carbon dioxide replacing the oxygen.) Only thanks to thermal updraft more oxygen is supplied, sustaining the process.
Now in this case there is no such restriction - we don't need external oxygen supply - as demonstrated in the video, the flame can even burn under water! So why won't it burn inside the needle of the syringe? Why doesn't it spread into the syringe through the needle?