Greasy Fork

Very good script and it also works if you scroll down a fullscreen video. It would be even better if the comment section is also included below the description or an option to add it below, and the button directly above the description instead of it being in the header of the page.

Thanks @Høly Spirit, I'm happy to get a divine feedback :) For me the comments are completely eliminated, but it's possible to make a version with comments below the description. I will try to make it later. Or maybe I will make the toggle button work in 3 stages: description -> related vids -> comments -> ... Let's pray for it.

It would be better if the video stays and only the desc with the comments/the related videos are the ones scrollable. But if it isn't possible, it's okay. Maybe I can find or create a workaround myself. Thanks in advance.

On my laptop I also fix the player, exactly as you suggested above, but as I mentioned, for me comments are eliminated. Just create a new script like this:

// ==UserScript==
// @name        Youtube player fixed position for Høly Spirit
// @match       *://*.youtube.com/*
// @grant       GM_addStyle
// @version     1.0
// @run-at      document-end
// ==/UserScript==

GM_addStyle(`
  #primary-inner { 
    position: fixed !important; 
    width: calc(var(--ytd-watch-flexy-max-player-height) * (16 / 9)) !important; 
  }
`);

However it's not a perfect solution, you will see if you use it for a while. Also cinema mode (dark surroundings) does not work.

Hi @Høly Spirit, try it: https://greasyfork.org/en/scripts/449600-youtube-right-side-description-comments-related-vids-with-toggle-button

@barn, I found a solution to fix the position of the player.

// ==UserScript==
// @name        Youtube player fixed position for Høly Spirit (v2)
// @match       *://*.youtube.com/*
// @grant       GM_addStyle
// @version     1.0
// @run-at      document-end
// ==/UserScript==

GM_addStyle(`
  body {
  overflow: hidden; /* Hide scrollbars */
  }
  #secondary {
  max-height:calc( (var(--ytd-watch-flexy-max-player-width) * (9/16)) + 10vh) !important;
  overflow: auto !important;
  }
`);

A better one using a bad way of hiding the scrollbar.

GM_addStyle(`
  body {
    overflow: hidden; /* Hide scrollbars */
  }
  #secondary {
    max-height:calc( (var(--ytd-watch-flexy-max-player-width) * (9/16)) + 10vh) !important;
    overflow-y: auto !important;
  }
  ::-webkit-scrollbar {
    width: 10px;
  }
`);

Thanks. Not that 'bad'... gonna use it for a while if everything ok with it.