Panasonic just announced the LX100 which is essentially a Panasonic GH4 in a smaller body with a built in lens (that's a Leica f1.7-2.8!) It shoots 4k at 24/30p, 1080 at 60, etc. Expected price $800-900.Yeah it's essentially doing 24 photos a second w/ audio.
The development of the app probably wasn't expensive (he did have some industry professionals beta testing and advising him though), but it's more that you can't get a device that shoots quality 4K footage for that sort of price. Most bodies alone would cost more than a grand, and then you need lenses, batteries, storage, etc. He's offering decent-ish 4K at what's technically a low price.
This app is dead because of the price. It's a neat idea, but the form factor of the phone for professional video shooting means it's nothing more than a novelty, and a novelty is wildly overpriced at $1000.