Any gadget that gets you off your ass and moving can be a benefit.
There are many advantages to having a treadmill around the house. You can run in any weather conditions. You can run naked (seriously) or wearing only underwear. You can CONTROL not only your speed but the grades you run. In fact, if you want to do hill training, you are at the mercy of the terrain where you live, and you must necessarily run both up and down hills. With a TM you can run on a grade perpetually, and never have to run downhill.
On the road, you can fool yourself about how fast you are runnung; not so on a treadmill.
Treadmills are easier on joints than pavement.
Interval training is easier on a treadmill, where you can exactly control your speed, time, distance, and rest periods.
I personally have a pretty good treadmill with adjustable speed, incline, and a heart monitor. I have mounted a television in front of it, which makes hour-long "power walks" or whatever else I want to do incredibly convenient. I can pick a show I want to watch and walk or run without even thinking about the time lapse.
After 35 years of being a "runner," I finally wised up and stopped distance running, although I frequently enjoyed the experience. It is simply too hard on the joints, and the cardiovascular benefits are terribly over-sold. Interval training, coupled with body-weight training, stretching, and vigorous sports activities are the best way to stay in shape.
I have never used my treadmill in the same way as the person in the video at the top of this thread.