Audio – Visual used to be stills only, often ingeniously programmed, so that audiences sometimes commented on the “video” they just had experienced.
Not often that I use video only, mostly it’s a combination of pictures and video which make rounded shows, usually pleasing to watch. There is the exception, where I first “mislead” the audience, only to surprise the viewers. Check RoS, Link…………………………….
Sound should be dedicated to fit the visuals not “one-fits-all” as we see on some product presentations / instructions In YouTube, Facebook etc.
For spoken instructions, I might not want to use back-ground music at all or at least very subdued.