There’s just a big ol’ heat sink covering most of the board. Even under sustained 100% CPU load, I’ve never had it getting any hotter than 72° C, which is not even close to the maximum operating temperature of 105°. It’s sitting under a desk in a corner with practically no air flow, almost completely enclosed from all sides.
You might need some limited active cooling if you are using the device for gaming, like a large and slow fan as shown in the video, but I wouldn’t be surprised if you can get away without it.