Re: The video
The El Reg story is missing something - this is not the first flight test of the Magnix engine in a commercial airplane - that was in December, in Vancouver, Canada, with Harbour Air testing it in one of their DeHavilland Beaver float planes. There is a video of the first flight (with sound) from a wing-mounted camera in this article: https://www.flightglobal.com/aerospace/harbour-air-to-resume-electric-powered-beaver-flights-as-certification-work-begins/136071.article
Harbour Air is a local airline serving the BC south coast with float planes making mostly short hops between city harbours, which makes them a good candidate for electric motors with relatively short battery life. They operate a variety of float planes including the Beaver and Cessna Caravans. The float planes have a reputation for making quite a racket on take-off from the harbour, so anything to reduce the noise would be welcome.