You’re as likely to have first encountered Dave Franco — yup, that’s James Franco’s younger brother — in his series of outrageously raunchy Funny or Die videos as his roles in films like Fright Night and Charlie St. Cloud, and TV shows like Scrubs and Greek. (In case you haven’t seen them, click here and here to watch the very Nsfw videos.)

This week, Franco’s twin career paths converge at the SXSW Film Festival: 21 Jump Street, featuring Franco’s biggest film role to date, premieres Monday as at the Austin festival’s centerpiece film; and the night before,...