Two girls sit in a bus stop and begin to tease a younger girl. As they throw cruel taunts about her audition for a school play, tell her she needs makeup and ask if she has any friends that "aren't imaginary", passers by come to the victim's defence.
Set up as a social experiment, the footage was created by US entertainment network UPtv and captures a trio of actors and the impressive responses from bystanders.
Reactions from strangers vary with one telling the bullies to "Quit messing with her" and another saying, "This is how you bring people's self-esteem down".
Others attempt to draw the victim away from the situation as one woman offers to sit with the girl on the bus while a man calls her over to play his harmonica for her.
Created in support of National Bullying Prevention Month in the US, the "Stand UP Against Bullying" video has been viewed almost four million times and shared over 100,000 times.
Commentators responded to the video with messages of gratitude and support.
Kelly Venn said: "I love the older man who starts playing his harmonica for the bullied girl. It felt like he was reinforcing the 'everyone's a little different, and that's ok' mindframe just by that simple act".
While another shared details of her own struggle as a mother with a child victimised by bullies.
Tara Wallace posted: "This was so great!! Thank you for doing this. As the mother of a bullied child who was bullied so badly he contemplated suicide. I had to end up home schooling him. He is so much better now and will graduate this winter. These kids do not realize that one mean comment can really hurt a person. This needs to be shared as much as possible".