She had no idea I played the video. I paused it without saying anything and she said it went away, then clicked on "play" again and she said "There it is again! What is that? Where is that hum coming from?" This is the honest truth.
I think it depends on whether you can hear low-frequency sounds; obviously, your daughter can hear it clearly.
I’ve heard it myself in Taos - I was with two friends, only one of whom could hear it along with me. The one who couldn’t hear it thought we’d lost it, but both of us heard it quite clearly. There’s a similar noise here in the eastern Czech Republic, though it’s not always easy to hear, as there’s a small commercial airport nearby, but if you go into the surrounding forests - we’re near the Western Carpathians - you can hear it on a quiet night. It’s audible provided you can hear low frequencies.
Is there a random electronic noise on that video? I don’t hear the hum but it sounds as if the recording equipment isn’t good.
Do you have a sub woofer on your computer? The bigger box that sits in the middle. Without a sub woofer your computer would not be able to produce low freq sounds.
Sometimes you lose fine hairs in your inner ear as you age, and with them, the ability to hear certain frequencies. I remember some company offered ringtones for phones which were inaudible to people over 20 years old or so, because the specific frequency they used exploited this. Kids got the ring tones, so they could hear their phone ring in class, without their teacher knowing.
Could be similar.