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Allows the user to toggle autoplaying to the next video once the current video ends. Stores the setting locally.
This userscript is now being maintained by 𝖢𝖸 𝖥𝗎𝗇𝗀, available here.
Some time ago, YouTube stopped providing the option for users to control autoplaying the next video within a playlist. This change disregards playlists such as Watch Later, where you may want to stop at the end of the current video or wait until the end to comment. (Especially problematic if the video in question doesn't have an end screen which would give you time to pause before the main content ends.)
This script works by controlling the property "canAutoAdvance_" which is set by YouTube. When this property is set to false, the playlist will not autoplay the next video. Unlike other scripts affecting this property I had seen - which repeatedly attempts to set this property to false as it fights with YouTube changing it - my script replaces the functions YouTube uses to control the property, achieving full control.
After installation, an autoplay toggle switch will be visible in the playlist headers on YouTube's website. Toggled left (default gray) prevents autoplay and toggled right (default blue) allows autoplay. The status of this toggle is stored locally and restored when the site is visited again from the same browser, so long as localStorage is not cleared.
Note: I originally made this for personal use, digging into YouTube's code and examining how other people attempted to address this and similar issues. If it breaks for a while, feel free to put out your own fix.
