I watched this video yesterday by coincidence . I was keen to know about making learning addictive. And honestly, I liked the video, it was funny and informative. And it is interesting that you can turn evil manipulations into positive ones. I didnt know the presenter was the founder of duolingo and he was from Guatemala. I use duolingo to learn languages, I am not sure if you can really learn a language this way (at least I am not that smart) but it helps to practice a little, and then the compound interest should get you to some decent level. This remind me to brilliant. It is something I wanted to use, but at the end of the day, I dont have time for all things I would like to do. I need to focus in the things I really need to do.