As the star of Spider-Man, Andrew Garfield can probably tell you that there’s a lot of power in a costume. There’s also a lot of vulnerability as well, as the actor illustrates in “We Exist”, the new Arcade Fire video. The clip finds Garfield playing a character who is struggling with gender identity issues in a small town. She goes from wistfully watching an old couple in love dancing, pining for the type of open affection that’s withheld from her, to being asked to dance, then promptly beaten up. From there things transform into a dream-like fantasy, in which the rednecks become her backup dancers, and she joins the band onstage for a triumphant celebration. “We Exit” flashes on the screen. It’s a good reminder.