This one is a trailer for the story Broken Walls by Musicgirl553. Not much of the story has been uploaded, but what I read was pretty good so far. The story is an Arrow/Flash fanfiction. I've never seen the shows, but after editing this trailer together, I kind of want to. 

This is the description from the story itself: 
Madelynn Coleman spent a while in Central City, to help save people with Barry Allen. Although her hero name, Silver Banshee, sounded like a villain name, she used her banshee scream and telepathic powers for good.But, returning to Starling City, she once again reunited with her friends: The Queen family, Diggle, Laurel, Felicity, and Roy. Roy and Madelynn only met a few times, but now they were getting closer.Sadly, upon the horizon, lay a metahuman battle, one that will be remembered in Central City and Starling City for a life time.Will love get in the way at the task at hand?