Teaching computers how to understand actions in videos is tougher than getting them to understand images. "Videos are harder because the problem that we are dealing with is one step higher in terms of complexity if we compare it to object recognition," says Dan Gutfreund, a researcher at a joint IBM-MIT laboratory. "Because objects are objects; a hot dog is a hot dog." Meanwhile, understanding the verb "opening" is tricky, he says, because a dog opening its mouth, or a person opening a door, are going to look different. The dataset is not the first one out there that researchers have created to help machines understand images or videos.