it could be mildly interesting as an indy short comedy, but only for Bieber haters.
Very niche, I also feel there isn't enough in here to make it anything more than initial amusing and imagine repetitive jokes and tired cliches.
However, in an attempt to be constructive I would suggest tweaking the concept, remove Justin Bieber as a character, to be more of a peter pan coming of age comedy marketed to older teens and young adults. This would open the door for all those awkward teen moments (kissing for the first time, trying for second base, etc) and failing horribly as he/she has even less of an idea than all the other kids as they have been off in a castle/forest/cave/bin/dream land/space, etc.
I would make it more about the comedic quest for adulthood rather than seeing a famous persona in unlikely situations, but hey that's just my opinion, feel free to discard (or use) as desired.