Umm well a new thread wasn't probably necessary, but I believe the key to this is in a huge number of repetitions
I think I had my camera on continuous drive mode shooting as fast as it could while I kept igniting as fast I
could. As for exposure, depends on what you want. A longer exposure gets you sparks drawing long straight lines and a shorter one may give you a nice clean view of a gas explosion. I believe I used 100 us shutter time and if I'd start playing with a lighter again I'd start with something slower.