I decided to make a compilation of clips of the seiyuus being chaotic at MHA events this time :) Please note that I am by no means fluent in Japanese, so the subtitles may not be 100% accurate.
Sources (in the order that they appear):
Season 3 Line live https://www.youtube.com/watch?v=GdofO5iLizY&t=859s
Jump Festa 2018
Two Heroes Press Conference 1 https://youtu.be/1oESg9_Gruo
Two Heroes Press Conference 2 https://youtu.be/n32tAzv8En4
5 Year Anniversary Live Stream https://youtu.be/3nleQaPULYc
HeroFes 2020
Hero Day 2021 Live Stream https://youtu.be/iUhMNMLCS68
Team Fatgum Press Conference
Season 4 Live Stream
World Heroes Mission Live Stream https://youtu.be/txLsTijwulc
Two Heroes Livestream https://youtu.be/n32tAzv8En4
If you'd like to follow me on Twitter, my account is @orchid4hire. I don't really post anything, but it's the best place to reach me directly :)