The "magic dust" they would dramatically toss into the fire to begin each tale was coffee creamer.
If you're looking for something for your own fires to mimic the vibe (that doesn't last for less than 5 seconds), I highly recommend this: Mystical Fire Campfire Fireplace Colorant Packets (50 Pack) https://smile.amazon.com/dp/B00KMASB4U/ref=cm_sw_r_cp_api_glt_fabc_2M8H627FP05YP4RTYN71
God how I miss this show!
If you don’t mind other colors popping up besides green there are these awesome little packs called Mystical Fire. You put a couple sealed packs in the fire and it changes colors, mostly green and blue but others also.