In this day and age, I could just see someone putting something like this together with a dubbed soundtrack to create a humorous fiction. In this case, however, the truth is stranger.
That’s a DoobleBug harness with its Radne engine replaced with a small jet. It’s just a demonstration, and not something that will ever be for sale anytime soon. Powered hang-gliders have been conceived and produced for a while, in various configurations, but I’ve never been attracted to the idea of a prone harness like the Mosquito and others. Even though I’m quite used to flying prone (Superman) and have endured for up to nearly four hours, there’s an uncomfortable aspect to it. Of course, we fly that way only partly because it offers a unique viewing perspective; mostly it’s to greatly diminish drag. But if you’re under power, that much drag is simply not a concern, so flying upright is the way to go.
I’ve sat in that harness in a static display and it feels just right. I happen to have a large-surface-area hang-glider with a low aspect ratio that would be perfectly suited to a DoodleBug, so I’ve definitely thought about it.
Update: Ah, here’s a video of someone launching in a Mosquito harness: