Here at The Writing Center, we run something called the Digital Video Workshop at least a dozen times (most likely more) every semester.
In it, we talk about how different elements of a video work together to create meaning. There are both visual and audible elements in any video worth watching, and if it’s well made, the sound matches what you see. In fact, doesn’t just match it; it frames it. The sound takes what you see on the screen, and changes the way you process it.
And if you don’t believe me, see if this changes your mind.