This really is nothing new and to an extent they will work but only on certain types of dents and possibly only on certain vehicles. Most I have seen and a couple I have used basically work like a windshield puller. Basically you bridge the dent and then you pull the dent out with another suction cup sometimes attaching via superglue. It just depends on the dent and its willingness to be pulled out.
Most of the time I have had better luck working from the other side rolling them out, sometimes with as little as a spoon. Important in any case is temperature if you want to maintain the paint.
Another method I have seen demonstrated involves induction heating which if done carefully can also preserve the paint.
Perry