EDIT – does not work anymore see comments
Something I do often – I sort my Watch Later list in Youtube by how long the videos are. I think its “shortest video to get the quickest entertainment bang for my time” (which is semi sad).
I wanted to automate it. Found several dead ends: Youtube doesn’t let you use their App Scripts API to modify the Watch Later list, and the page doesn’t let you run a bookmarklet to load an external js file.
Ctrl-Shift-I, Sources, >>, Snippets
That’s my solution for now. It gets what I need done. I wish I could have done that more generically.
Thanks to Matt H. for pointing me down the path of Chrome snippets. That dude is bright.