I would say that the video is genuine.I had an engine failure while instructing a student in a PA-28 in march 2000. I talked through what I was doing to keep him and myself calm. Landed in a field with no damage.
Lipo batteries have gone on fire when punctured or on rare occasions while being charged. I've never heard of a faulty speed controller directly causing a Lipo battery to ignite.What has happened is that the speed controller itself has gone on fire and this fire could spread as any fire can spread throughout the model