>>156168It feels like videos are much more attention captivating than music. As such trying to use them as "background" is a fairly contradictory task. Since one or the other will command your full attention to comprehend, and if you don't think so and believe you can forget what you're watching easily then you're most likely wrong. In that case you're taking nothing in from either activity you're doing. Most of the stuff you remember from "background videos" is from them taking up more of your attention than the primary task you were doing. Although if what you're doing is nothing and menial then it's probably not that big of a deal since you just wanted to watch the video and that's why you're doing a menial task. Otherwise music doesn't engage your brain to think too critically about it or follow along to a thought thread like a video would often have you do.
Of course that's mostly speculation on my part since I haven't really read any studies for how the brain engages music vs videos, but it's certainly how it feels.