Best reaction video I saw, and it’s not the traditional genre but a guitarist at a guitar show was doing a demo for acoustic amps.
He asked for a volunteer singer from the audience. A women duly stepped up. He asked if she knew the song he was about to play and said “you’ll need to stand closer to the mic as the amp will be loud”
“I won’t need the mic”
“Honestly this thing is turned up loud to be heard above the crowd (indoor exhibition)
“No I’ll be fine”
Looking exasperated he says ok and starts to play the intro demonstrating how loud it is.
She then proceeds to sing so loud (and perfectly in pitch) that you can’t hear the guitar!
The look on his face is priceless, he genuinely didn’t know she was a well regarded professional opera singer!
And long story short she now reacts and critiques songs on YouTube on her channel The Charismatic Voice
Viewers suggest songs to her, her reaction to heavy metal, RATM (you can guess the song) and particularly Rammsteins Sonne (snow white spanking dwarves) video is hilarious