There are a lot of posts on PG.com and other GMAT websites where 2minute gmat is advertising very subtely.
For example, http://www.pagalguy.com/discussions/how-i-scored-in-the-top-1-gmat-760-25051949
Notice how only a single point refers to the use of 2minute gmat.
There are a large number of posts all over the web like this. I will keep posting those links as and when i come across them.
I am sure about this being an advertising gimmick since I regularly read posts by GMAT takers, and go thru their list of books/resources used.