here is what I see when I just came to the page :
https://ibb.co/6s4ymh8
And if I click on the Play icon :
https://ibb.co/m5Q3N3c
It’s the same message that we can see on a youtube video that is private like : https://www.youtube.com/watch?v=_n8aLik_qTs
And yes, I made the API KEY with the same google/youtube account that hosts my video..
I set no restrictions on my api key, so “localhost” shouldn’t be a problem, right ?