There have been countless articles, discussions and opinion pieces in print, online or in bars and staff canteens attempting to dissect the trick's every detail and explain or reveal how it was really done. The theories doing the rounds are various.
But it's all academic, isn't it? The trick's purpose was, in the first place, to delight and entertain, wasn't it? At the time that it was performed it seemed like magic. With every subsequent viewing it still looks like magic, but a little differently so every time. Scrutinising it is enjoyable, yes: especially if we are, or want to become illusionists too. Being unable to tell with certainty how it was achieved - even if we swoop on little clues here and there to proclaim a possible solution - goes a long way towards proving its worth.