The video opens with a guy rapping on the window of a van.

"Brother, who are you?" the person holding the camera says. "What are you doing? I'm with the news, dude."

You can see hands holding the steering wheel from the bottom, but the man inside the Ford van, dressed in a full driver's seat costume—including a face mask—doesn't react.

Later, the camera operator (reporter Adam Tuss from NBC's Washington, DC, affiliate) is in a car that's driving next to the van, and, as his camera peers into the window, the ghostly movements of the steering wheel make the van look really, truly autonomous.

MYSTERY SOLVED. Here's why a man dressed as a car seat drove a "driverless" car around Arlington this morning https://t.co/DZdvXDedJ2 pic.twitter.com/9ejVuQttJy — NBCWashington (@nbcwashington) August 7, 2017

NBC 4 in Washington, DC, published the video this afternoon. Soon after, Virginia Tech's Transportation Institute (VTTI) told the station that the person driving the car was a researcher who was conducting a study on how people reacted to driverless cars. "The worker was wearing the uniform he was supposed to wear," VTTI told NBC 4.

In a statement, the institute clarified: "The driver's seating area is configured to make the driver less visible within the vehicle, while still allowing him or her the ability to safely monitor and respond to surroundings."

We're just going to break this one wide open, sheeple: maybe this is how self-driving cars really work. Although we've reported from the back seat of fully-autonomous vehicles before, no one ever thought to check the low end of the steering wheel for hands. Open your eyes!

Ars reached out to VTTI for more details on where the organization buys or makes its costumes, because this writer believes that Halloween is best spent sitting silently, in perfect camouflage, meticulously obeying traffic laws. (NBC 4 did note that other pranksters have tried similar costumes, but none were quite as good as VTTI's, from what we could tell.)

But VTTI couldn't make any researchers available to us for an interview because of the late hour. The institute did, however, send us some vague information about the autonomous vehicle study it's currently conducting. The study is apparently "one of many being conducted to determine how best to design automated vehicles," including the need for additional indicators on the outside of the vehicle so that humans in the vicinity know what they're driving, biking, and walking next to.

VTTI added that the driver's costume is perfectly safe to drive in. "Development of the test vehicle focused on ensuring driver safety and included several months of piloting and testing the vehicle, first in controlled areas, then in low-density areas, and finally in an urban area."