It's really choppy on my computer, but I'm definitely finding it interesting on a few levels. In case you actually want to understand people that appreciate this kind of art, here's my take:
The basic level for me is that watching them run around is kinda compelling. I once worked out of a high office building across the street from a building being disassembled and then replaced, and I lost hours watching the people at work.
There's also a series of deadlines; watching them speed up and slow down is neat. Very human. Will they make it? How about next minute? A friend who's an improv performer (and Google engineer) sometimes does this thing at his shows called "the oxygen game". Three people improvise a scene, but only two are interacting at once. The third one has their head in a bucket of water until the other two find a narrative reason to bring them back in, at which point somebody else's head goes under. The audience loves this human struggle against time.
There's also an element of expectations violated. Clocks are usually utterly boring, especially digital ones like he's aping. Which is why a lot of people create interesting clocks. E.g.: http://www.stuartsinger.com/ballclock.htm http://longnow.org/clock/
Then when watching it, it's really interesting to think about the labor. These are real people, in effect dancing for our pleasure. But they're not professional dancers. They're just construction workers, making another thing for somebody else. How do they feel about that? Do they feel the same way about a lot of the stuff they get hired to build? Are there other things that they build that are ultimately just as pointless, just as rooted in entertainment for the funder?
Then I wonder how far you could take this. What if I put up a webcam in Times Square and had a big mechanical clock where people had to supply the labor. Say by cranking a wheel once a minute. Would people participate? How would they feel? Would the clock ever miss a minute? Would it miss an hour or a day?
So for me, art like this combines an interesting idea with something that engages the senses (and sometimes the emotions) long enough for me to think about the idea and related themes. Nothing new, really: Cathedrals weren't just built to be pretty; they were there to get you think about the builder's god(s).