I would second the opinion that having that thing in your house and breathing deeply around it wouldn't be a great idea.
Looking at the video I'm somewhat puzzled about what their justification is for claiming this was the "first Macintosh 512k off the production line". No evidence is put forward to support that. (I'm guessing they mistook the "M0001" model number for a serial number.) Further, the unit is in terrible shape even before it's microwaved. It's filthy, yellowed, and the CRT is de-laminating. I'm sure it came out of an electronics recycling bin. From that point of view I suppose you can't really claim that microwaving it was a "waste" of anything, but... I also fail to see the "art" here. At best it's a "performance piece". Once the microwaving is over it's just scrap. (And it's not even an interesting performance. It smokes a little then catches fire. A time-lapse in a regular oven would be more interesting as you'd probably at least get some melting before the flames start. At the very least work out some way to have the machine running with something on its screen as it's nuked. Loser.)
Maybe after the next Fourth of July I can eBay my used sparklers for fifty grand. "Display proudly and imagine the brilliant display... that stopped once they were no longer on fire."