According to Wonderopolis, a video goes viral when it tops 5 million views, typically in a very short time and due to multiple shares on social media.
Over 18 million views strikes me as viral.
This video, posted by Pall Sidgurddson in April 2019, showcases both how pollution in the form of marine debris has impacted nature AND how connected the human and natural world can be. The video details scuba divers helping an octopus replace its plastic cup shell with something far more protective. You can learn more about the dive and experience on Upworthy's article entitled "Kind Scuba Divers Try to Convince a Tiny Octopus to Trade its Plastic Cup for a Shell." This one small act of kindness potentially saved both this coconut octopus and any potential, future predators from consuming that plastic cup.
One small act of kindness always makes a difference!
Video from https://www.youtube.com/watch?v=DTJbdy097m0