Why the boosters videos aren't offered me anymore?

Hello @FernandoSousa and welcome to our friendly community.  I'm sorry that you lost the opportunity to watch videos to get free boosters.  Some people have the opportunity to watch ads,  however, not everyone has access to this and some people who do have access may not at a later date.  The studio is always looking at ways to keep the game interesting and challenging and as a result, they will periodically pick a random group of people and give them access to an event or feature and sometimes they will remove access to a certain event or feature.  In this case, you are unfortunately no longer part of the group that has access to watch ads.