Amy Kistler has seen a man dancing on the 20th Street pedestrian overpass above Highway 101 for years. Her evening commutes from Emeryville back to San Francisco are speckled with sightings of the dancing man, who always holds a large red heart in his hand. Stumped, Kistler asked Bay Curious, “What’s the story with the dancer on the 18th Street overpass?” Video: Lucas Waldron, Adam Grossberg