Mark is Guilty. Ethan Has the Proof.

Summary
Mark and Ethan use a Smithsonian Fingerprint Kit to investigate a make belief crime scene in search for stolen school supplies. Nearing the end of the video, the two inhale a powder that allows them to go back in time and prevent the crime from ever happening. In a post-credit scene, Mark fingerprints Chica's paw and accuses her of theft.