Ideally I suppose you'd want to film it with the array in various z-positions from the rear to the front, then composite all the versions together, perhaps with each version given a color overlay 'in post' to keep them distinct. Probably want to disable the microwave's interior light, and have the microwaved bulbs be the only source of light.
IIRC it's not so much a clean glass as a polished glass. If it's a regular cheap ass glass then it has enough imperfections that it's unlikely to ever happen with tap water. However polished glass (where the inside is actually sanded/polished smooth to remove imperfections) is the dangerous one, especially with distilled water (why anyone would drink distilled I don't know) or I suppose even filtered water would increase the risk exponentially compared to tap that can contain sediments from pipe scum.
http://www.youtube.com/watch?v=1_OXM4mr_i0 (Mythbusters exploring it)