I would really appreciate if you added an option to completely hide the video thumbnails (making them grey).

Works as intended! The results are quite welcome, seeing how bad clickbait can be on YouTube.

It would be great if it had a whitelist feature, the idea being that it won't change titles and thumbnails for whitelisted channels.

Overall, great extension, but I do have some features I'd love to see added:

The ability to change all-caps titles
Stretch the thumbnail image, so it fills out the entire box, not including black bars