So –– the source code above got scrambled badly. And it also turned out to be a little bit more complex to solve this reliably.
I’ve created and will maintain a gist on GitHub with my current solution:
https://gist.github.com/hirasso/32152de5d84dbcf1c194ea9217db6166
It creates a hidden custom post type to cache oEmbed responses from fields on options pages or the like.
