Of course, he didn't tell us what he was going to play. It is simply not possible to actually play that on piano. The composer, Conlon Nancarrow, manually cut holes in piano rolls to create a kind of non-electronic, electronic music. Here is another sample:
Half the students were asking themselves "why is the music never changing" while the other half were thinking "listen to those interesting changes". Here is another sample:
Scroll ahead to anywhere in the middle and ask yourself these two questions:
- What is the meter?
- Where is the downbeat?
One more? Ok, what is going on in this piece?