At first, I thought what a weird video, next I felt sad realizing this is exactly how it works. Fortunately for this child, he was still open for other children but what happens if children don't have friends and no one will invite them to come over to play?
I am afraid that if parents are mainly busy with the phone a day out together will be affected by phones too. It's no fun to be in company with people who always stare at their phones. How busy can one be? I experienced it myself. We went out to a restaurant with a group and everyone except me and one other was bought with their phone. So you sit like an idiot surrounded by people who are busier chatting with their phone than those they share a table with. I find it rude.
In the case of the video it has a happy end, the phones are scared to death (let's hope they will not act more aggressively.