That's the beauty about busking. You don't have to have a huge amp system, you don't need twenty other musicians, you don't even need an actual venue. You just play. Of course, these two most likely practiced their routine repeatedly beforehand, but the fact that they are willing to put themselves out there and play in front of millions of traveling New Yorkers is really inspiring.
As for my busking experience, I'm still working out all the variables. I'm hoping to get a guitarist and maybe a few other percussionists to accompany me, and of course someone has to document the performance via video or photos. When I do, I hope you'll check us out!