The aspect ratio of a video is a subtle parameter that can have a large effect on the final product. This excellent video examines the different things you should consider when choosing an aspect ratio for your work and how they'll affect how your viewer perceives the final product.
Coming to you from Studio Binder, this great video talks about aspect ratios and how to choose the correct one for your video work. The reasons different aspect ratios have different effects on viewers stem both from natural perception and the way we've been conditioned to think of them. While it's true that aspect ratios wider than natural human vision impart a sense of adventure and larger than life grandiosity, that sense is doubled simply because most of us were brought up seeing films that way, whereas television has traditionally been a less extreme ratio. This is why wider ratios are often referred to as cinematic. When you're choosing one for your work, it's important to think about not only the perceptual effects you want to have on your viewer, but the history of the ratios you're considering and how those will play into viewer expectations.