Rocks is an Action clip that is available for everyone to use in the Movie Maker. The clip is used to make Edgar or Eva rock out with a guitar. 13, on the other hand, smashes the guitar on the ground, which breaks it. The duration of the clip is 3 seconds.
If Edgar or Eva are the secondary characters in the clip, they will be headbanging with headphones on. 13 does the same thing, but without the headphones.