That was a great example of the same issues I get - no problems getting powerful sparks and arcs, the issue is where they happen and where they should be! I have burned the insulation of several magnifier transformers so now I am looking at transformerless magnifier designs. These have been analysed by ACMdQ and might be easier to insulate.
OMG, that's plain awesome... Unbelievable performance for such a small coil! (if it is that hanging below the topload). It demonstrates the true capabilities of the magnifier type tesla coil. The specific shape of the topload could play an important role here too. Can you please tell the specs?
