I’m currently in the process of switching from YouTube to Piped and was getting fed up with rewriting YouTube links myself. I finally found an extension that can do this with a relatively easy setup:

Redirector Firefox

Redirector Chrome

Thought maybe more people might find this interesting. My setup is in the pic.

Edit: @nutbutter@discuss.tchncs.de Just suggested using LibRedirect which is even better than Redirector. Also since Redirector isn’t really maintained anymore.