The Oscar-nominated short documentary “The Barber of Little Rock” follows Arlo Washington, a barber who is trying to close the wealth gap in the city. As Katie Porter exits her House seat, two Democrats vying to replace her are airing nasty attack ads. Could this swing the district back to a Republican? In “Filterworld,” author Kyle Chayka examines how algorithms built into apps like Instagram, Spotify, and Netflix dictate our choices and erode our individual taste. Red velvet cake tends to come up during Valentine’s Day. Beyond all the food coloring, the pastry’s biggest characteristic is its slightly tart flavor.