This is a Tampermonkey/Greasemonkey script. When enabled, hover over a YouTube video's thumbnail (the image icon of the video) with your mouse while holding down assigned key.
Shift key = "Not interested", "Recommend less like this" & "Hide"
Alt key = "Don't recommend this channel"
18/11/2022: Added another "keybind" that should make it future-proof because, for some reason, YouTube likes changing the name of selectors.
11/25/2021: YouTube changed its page structure, so I updated the script. Also add support to hide videos on right side of the video watching page.