These are fairly experimental and may affect performance or stop working at any time. Feel free to comment if you have any better implementations, I tried to be both as specific as possible and follow reccomendation from the documentation, though I am just a guy.
The files are (at time of writing) are .ubo files (for UBlock Origin) though I dont believe this is an official file name.
All these were testing using AdNauseum, a skin of UBlock Origin.
Instructions on how to use these located here: https://www.ghacks.net/2014/10/10/how-to-add-custom-filters-to-chrome-ad-blocking-extension-%C2%B5block/ (the particular tab may be called "your filters" or "my filters")
I am not directly affiliated with UBlock Origin, AdBlock Plus, Youtube, nor their developers.
Is there anything that blocks those tiny, annoying, merch ads that now popup in the player, and refuse to go away except for a short while when you click to close them? I'm not sure it will work, but I'm thinking that this might work (you might want to add it to your list here if it will):
##.ytp-featured-product-container
##.ytp-suggested-action-badge-with-controls.ytp-suggested-action-badge-expanded.ytp-featured-product.ytp-suggested-action-badge.ytp-button