The most recent youtube UI updates have REALLY been grinding my gears, so I found this beauty and OH MAN has it been a breath of fresh air. I love the ability to peer into the past with the original yt layouts as well as simply flashing back a couple years into the past for more modern yet still beloved layouts. It's everything I ever could have asked for and then more. My only complaint is that the layout seems to be just a *little* broken in very small ways- buttons on the side bar have buttons missing and offcentered text in the 2019 layout, and sometimes when switching to an older layout the video details, comments, and recommended videos simply don't load at all. I'm also using the addons "Youtube search fixer", Sponsorblock, and an adblocker, so it's possible that this could simply be because some of the addons are not fully compatible, but I'm not totally sure of this yet. Either way, I'm looking forward to seeing future updates! It's definitely an addon to keep your eyes on, especially if you're like me and you hate the minimalist, modernist UI that every website and their mother seems to be adopting these days and pushing without bothering for any form of user feedback and critique.