Here's what I can tell reading the article...

Not particularly revolutionary, tech-wise. It's a low-cost solution, after all, not a new advancement. But the idea is pretty decent for giving access to hobbyists.

This gadget is not the camera or sensors or whatever else, those are old tech. What it is really is is a pressure-resistant housing and buoyancy-control in which you can put a camera and other sensors.

You drop the device, it sinks. After a predetermined time its buoyancy system returns it to the surface (the traditional way is to drop ballast). When it hits surface I am guessing it emits signals so you can boat out there to pick it up. You retrieve it and look at your video.

Just a heads up about underwater exploration: if you want to control just about *anything* (or get video/readings while it's still down there) you need signals. This means for anything deeper than 100m or so, either you run a cable or you use acoustic signals (radio's range is terrible underwater). Either would raise costs a LOT. Because acoustic signals have a HUGE latency, it is impossible to deftly control anything with them, nor can they effectively transmit video. This is why most ROVs (Remote Operated Vehicle, an underwater drone which can be as small as a backpack to the size of a tank) instead use an umbilical cable with fiber-optics. These cables are expensive as heck, because they're kilometers-long, armored (I mean you don't want a sharp rock to slice your cables right?) and filled with power cables and fiber-optics. The winch and umbilical for very large systems can cost millions. But this is literally the only way to properly pilot a system that is kilometers deep. There's also some hybrid systems where you lower a cable with a transmitter to depth and then control the ROV using acoustic/radio signals from that transmitter.

You can bypass most of these issues if you opt not to control the device and only get your video/readings after you retrieve it. But this means you run the risk of losing your device every time you use it. A low-cost solution does kind of make this less painful, though it means you cannot put anything too expensive in it. What the Maka Niu has - camera, altimeter, thermometer, hydrometer (video, depth, temperature, salinity, in that order), they are all very cheap (cept the camera - that can cost a lot depending).