The ways in which this blows my mind are numerous. For starters, it wasn't, as you'd at first assume, archived footage -- that is, the audience was not just watching a cleverly projected film of a previous performance. Digital Domain, the company responsible for the image, promises, "This is not found footage. This is not archival footage. This is an illusion." Note the boast here: it's not real; it's an illusion. It seems more and more like what impresses us as a society is not what's real but what isn't real.
1) This technology: so unfathomably impressive and advanced, it seems the stuff of science fiction
2) This technology: so old, it was first used by the Victorians
3) This technology: so mundane, it's essentially a movie