Edits have been made to this post.
It is an ad with two videos. Watch them and you get two prizes. One is a Stride By which makes the BFG walk across the screen, but you can only see his leg and shoes since he's so big. The other one is a Dream Trumpet which changes the color of other poptropicans.
We now have four prizes in total for The BFG; Giant Costume, Stomp Power, Stride By, and Dream Trumpet. If you look closely at the Giant Costume and the Dream Trumpet, you will realize that they both include the Dream Trumpet. If you customize the Dream Trumpet from the Giant Costume, you will realize that the Dream Trumpet powers are there too. So why do they need the Dream Trumpet twice? Is the power in the costume added after the Dream Trumpet was released?
Enjoy the prizes while they last!