The word "calientes" refers to the English word "hot," which is used to describe popular videos, such as the Mutant Giant Spider Dog or Bars & Melody Audition from 2014. Popular videos change all the time, according to what is trending or viral, but those with the most sustained views are considered "calientes" for that year.
Time Magazine put together a list for the most popular YouTube videos of 2014, which included Superman Vs Goku: Epic Rap Battles of History, Nike Football: Winner Stays and First Kiss. The Epic Rap Battle video had Superman and Goku perform rap battle against each other, leaving the decision of the victor the audience. The First Kiss video was created with several random volunteers that were paired together for a first kiss and the Nike Football video is a commercial.