Usage

On any YouTube video or channel page, click on the bookmarklet to instantly go to "Member's only" playlist of the video or channel owner.

Install

1. Copy content of membership-pl.min.js
2. Create new bookmark
   For Chrome: Right click bookmark bar and "Add page..."
3. Paste script in URL
4. Give name to bookmark and save

TL;DR copy and bookmark this:

javascript:(async function(){const a=await async function(){const a=["https://www.youtube.com/channel/","http://www.youtube.com/channel/"],b=[location.href];for(const d of b)for(const b of a)if(d%26%26d.startsWith(b))return d.split(/[%3F%23]/)[0].substr(b.length);const c=await fetch(location.href),d=new DOMParser().parseFromString((await c.text()),"text/html");try{return d.querySelector("meta[itemprop='channelId']").getAttribute("content")}catch(a){}}();if(a)window.open(`https://www.youtube.com/playlist%3Flist=UUMO${a.substr(2,22)}`,"_blank");else{console.log(`[MEMBERSHIP PLAYLIST REDIRECT] Cannot get channel ID on ${location.href}`);var b=function(){if(window.hasOwnProperty("ytInitialPlayerResponse")%26%26null!=window.ytInitialPlayerResponse%26%26window.ytInitialPlayerResponse.hasOwnProperty("videoDetails")%26%26window.ytInitialPlayerResponse.videoDetails.hasOwnProperty("channelId"))return console.log("Found channel in ytInitialPlayerResponse"),window.ytInitialPlayerResponse.videoDetails.channelId;var a;return Array.prototype.slice.call(document.getElementsByTagName("link")).forEach(function(b){"canonical"===b.getAttribute("rel")%26%26(console.log("Found channel link"),a=b.getAttribute("href").substr(32))}),a}();b===void 0%3Fconsole.warn("Could not find a channel ID at ${location.href}"):(console.log("Going to membership playlist URL"),window.open("https://www.youtube.com/playlist%3Flist=UUMO"+b.substring(a.length-22),"_blank"))}})();

Debugging and Troubleshooting

If it doesn't work try refreshing page before clicking the bookmarklet.

F12 to open console to see the problem. Comment below if something breaks.

How it works

The script grabs the channel ID which is 24 characters long and starts with UC.
Now for every channel, YouTube has kindly generated a playlist for its videos that are limited to member's only.
Let uniqueID be the channel ID without UC
The formula is basically https://www.youtube.com/playlist?list=UUMO<uniqueID>
After the playlist link is generated we just tell the browser to open it in another new tab and we're set.

Special thanks

Thanks to lekoOwO for more reliable method at fetching channel ID