Just the fact that all the Bronies documented throughout the movie had such a good time at the conventions they went to. Special mention goes to Daniel, the young man with Asperger Syndrome, who ended up having a great time at the convention in Manchester despite his general uneasiness around people and the fact that he temporarily got lost looking for the convention center.
John de Lancie himself performs a lot of Crowning Moments throughout the movie. Not only is he the person who came up with the documentary in the first place, he can also be seen helping Brony Lyle by talking to his skeptical parents, and even compliments the costumes of a couple dressed as Mr. and Mrs. Cake.
Pretty much the film as a whole. If you ever need to remind yourself what's so awesome about being a brony, just relax and pop it in.