If you look closely at the gif you'll see two black boxes just inside of each of the outside lightbulbs. One these boxes are two little nobs. Here's how I think it works:

the leftmost bulb swings into this block, triggering a momentary switch which informs a microcontroller (I'd bet 10 to 1 its an arduino), which then turns off the light on the left bulb, triggers the animation of lights through the middle bulbs, and then triggers a solenoid on the block on the right, which sends the rightmost bulb flying out.

I'm glad someone else was trying to puzzle out exactly what's happening here. It's obvious after about a second that more than momentum is at work. My guess is that there are wire coils in the thick part right above the bulbs and the current to power the bulb induces a magnetic field there. And if you were going to use a resonator circuit to do this, I'd imagine you'd need at least one per bulb. Then again, I'm a noob too, so there's probably some other amazingly simple way to do it all.