This is what works (attached):
the "v=" and the code following it (I believe it is always 11 characters following the "v=") are vital...if you see an ampersand in that code, STOP RIGHT THERE and don't include the ampersand or anything to the RIGHT of it...and you'll always be good
so TLDR; the link to a YouTube video must only include the "v=" and the 11 characters that follow, nothing additional