By the way, that "invention" is called the Hurley Delux 2000 Stretcher
But, these things are potentially very dangerous. And, the way most poeple misuse them, it only stretches the connective tissues at the joints. These never can be brought back to their original length and cause hyper flexibility of those joints, eventually leading to more injury.
The book/video by Thomas Kurtz that Derek mentioned is a real alternative to gain that stretch without injuring yourself in the process. There are also books and vidoes out there by Pavel Tsatsouline that use a similar method and are also very good. (search the name online, there's lots of stuff out there) These are real methods of training the muscles in your body to be strong in their most extended/stretched positons. This is how you gain those splits and do it w/o ending up in a wheel chair by the time your 40. The machines can be used as an additional tool to help you hold your max stretch position while you relax. But, forcing your limbs to a painful, overstretched position, beyond what your limits are, with high torque machinery is probably not a great idea. The crank will keep going long after you've torn muscle, tendon, and ligament beyond repair. Be very carefull with this stuff.
As a general rule, anything claiming to do something for you in a hurry that normally takes a long, hard bit of work to attain, is probably going to be very bad for you. Think Star Wars and the Dark Side of The Force.