Auto-redirect and Watchkinize
Watchkin Auto-Redirect userscript
This is a script for Tampermonkey or Greasemonkey, rather than a separate Watchkin browser extension. With a compatible script manager installed, open Watchkin Auto-Redirect and review the installation prompt.
The script sends YouTube video and playlist pages to Watchkin and preserves supported time settings. Its script-manager menu can toggle YouTube search redirects. It also converts YouTube video links on other pages; its access to those pages is needed for that behavior.
The updated script preserves its original name, namespace and download path. Automatic updating depends on your manager's settings and has not been verified with an installed manager. If needed, reinstall from the link above. Append redirect=0 to a YouTube URL to bypass the script for that URL.
Watchkinize bookmarklet
Drag Watchkinize to your bookmarks bar. On a YouTube video page, click that bookmark to open the video in Watchkin. Some browsers prevent bookmarklets from running on certain pages.
To disable automatic redirects, disable the userscript in your script manager. The bookmarklet runs only when you click it.