Yes this can happen a feather destruction bird can turn the destruction on to their friends. While preening their friends a loose feather may come out, the rapid number of feathers he is removing from his friend sure looks like he is pulling or clipping them out.
darn it ....good job in getting and sharing the video.
They are giving every indication they are great buddies here.
We all wish feather destruction behavior had a quick and easy fix.... unfortunately it's a complex issue...unless a health issue is the cause and thst is found and fixed.
As a star a complete overhaul of cage set up, toys , life , time out of cage , enrichment, routine, social time , flock observations done without preconceived ideas and story lines , observations and seeing what you see . Can offer insight . Can show dime stressors you weren't aware of , things outside, pets or people or things inside
I try and do this often , even when I'm not having issues. I ce think I had my green cheek start attacking my budgie with whole she had previously had a close and great relationship. ...so observed...to my surprise the issue was not between her and the budgie . Instead she was displacing to the budgie. The issue was between her and her best buddy quaker Neptune. He was guarding her, obsessing over her and all up in her space and never giving her a break. I switched how I managed the flock , and have her time out of the cage without him, time in her cage while he was out of his cage , and still time out together as they were bonded..abd set up mommy and me time with just my green cheek and I bonding and hanging out. This immediately stopped the attacks on the budgie and she never attacked him again. Sharing this , because I was quite surprised y my observations.
I think sharing pictures of your set up , walking us through your fault routine, could be helpful. We might see things that we could suggest you change that might decrease his stress and this behavior.
But knowing his wings are so short , I feel with certainty providing him with more ways to move around on his own , to be more active and self directed will help. Teaching foraging, engagement with more things to chew destroy, explore . One on one time with you , maybe teaching simple fun tricks even foraging together cover up a seed and have him find , and even doing some together with both birds will help. Foraging has to be st their level and very easy , in time can become more complex as they get a nack for it . Some never do , dime really enjoy it , but near all can have fun with simple foraging fun .
@Emma&pico has tins of fun activities for hers!