Everyone has to decide for themselves but the only problem is most people make the assumptions without testing the products in their own shop. It is easy to jump on the band wagon and discredit a product without any knowledge of what these are for. As for the product you are talking about, it does sound like a gimic using the running motor without oilpan and rocker cover. It makes a good show. Did they tell you what the base ingrediants are???
Regular motor oil is good enough to make an engine last a long time. That being said, there are products that will make them last longer, wear less, run cooler, reduce friction and create a few more horse power and or better fuel milage.
To find out the facts you can search out a product called Militec-1 which looks to be a good product. You can do a patent search for 5,885,942
and read the ingrediants.
You can read about Oil Extreme one of the most convincing articles at http://www.oilextreme.com/index.html scroll down to the motor tech mag article. Very convincing.
I am not endorsing either of these products because i use something else and have proven it to work. I believe in it enough to sell it myself
and only sell it to friends here at home. They always act supprised when their fuel milage goes up. I use it on drill bits, string trimmers, lawn mowers, any type bearings that are getting hot.
The most important advice you can get is to test some of these products out for yourself.