?rel=0 auto changes to %3Frel%3D0 when adding to end of YouTube link to stop related videos… Why?

Question

Sometimes on Facebook when I add the ?rel=0 to the end of a YouTube link to disable the related videos from showing at end of video, it automatically change that ?rel=0 to %3Frel%3D0 once I click Done Editing? Why does it do this sometimes and not others? What does %3Frel%3D0 do differently than ?rel=0 does? Or do those two do the same thing?

Also, can you add both &fmt=18 and ?rel=0 to the end of a YouTube link on Facebook?

Answer 1

%3Frel%3D0 is just the URL encoded version of ?rel=0

You can check it here. And can read more about URL encoding here.

Why this happens only sometimes and not some other times, I don’t know, but is exactly the same thing.

And I think the fmt parameter is deprecated, which means most likely it will not work.