'Cobra Kai' Star Mary Mouser Reveals She's 'Covered in Bruises' While Filming "Most of them are completely self-inflicted." Dec 29, 2020 The Karate Kid franchise, one of the most famous martial arts entertainment properties of all time, and the stars have the bruises to prove it. Mary Mouser, who plays Samantha LaRusso in the streaming show, talked about how the filming was physically demanding, although she admits that a lot of it was down to her own lack of coordination. "I have more than my fair share of mishaps," she told Digital Spy and other media outlets. "I'm a clumsy enough person before they gave me stunt work! And it just doesn't get any easier from there."