From a creative standpoint, speaking as someone that owns their own photography and editing company, without music, the viewer would get bored. Since Eddie chimed in, I'll use his and Cindy's videos as an example. Say they have a 20 minute video....if you watch it carefully, you'll notice that the music is ducked (technical term for lowering volume) in situations where, as you say, hearing the ambient sounds (be it engine struggling, parts snapping, someone talking, etc) is of importance. However, during general B roll, it's just boring. To illustrate my point, look at WAYALIFE's youtube channel and find the video of moby bombing through the desert with rock music....and watch the video on mute. It completely loses it's ambiance. The reason why you use music, say in a holywood horror movie, is to lead the viewer into an emotional state you want them to be in....be it suspense, sadness (think titanic), excitement, etc. Music is a critical part of any production, no matter how small, to keep the viewer engaged, especially when we are talking extended periods. To be frank, it separates the amateur from the professional. Futhermore, music, transitions, effects (ie Cindy's supercuts of Eddie opening boxes) add that little bit of something to make an otherwise boring thing (a guy opening a box) something interesting to watch. If you watch a low quality video about jeeping, you'll see the typical "hey guys, it's XYZ...so today I got these new tires, blah blah blah." Boring as hell. Now sure, some people overuse any and all of these "effects" which also makes the video annoying to watch, but overall, a good balance of all of the above is critical to making engaging content. A prime example (and I use it when I teach people proper video editing techniques) is to watch the WAYALIFE keep it tight series, vs the professional camera crew shooting a JKX event. It shows clear as day that no matter the equipment, the fundamentals of storytelling are basic, and can't be overcome if they are wrong with rancy RED cameras, $5000 Inspire drones, and $10000 rig mounted gimbals. It's an art. Finally, don't confuse a storytelling video vs a technical instruction video.