You may notice there’s no ignition system or fuel, so it’s not an actual combustion engine. Instead, it runs on air. At the end of the video the maker, one Yesus Wilder, pumps compressed air into it and while it’s not as meaty, it sure sounds like an engine to me.
The music is oddly… grandiose… considering the content of the video. Yet, it sort of works, if you can imagine there’s a tiny brigade of hobbits crafting the engine instead.