Since August 2018 showinfo and rel parameter doesn't work so answers which recommend to use them no longer works and modestbranding do not remove all logos
here is my tricky solution how to hide EVERYTHING
Before you start you should realize that all youtube's info are sticks to the top and bottom of iframe(not video, that's important)
Make iframe higher than real video height. In iframe parameters set height = width * 1.7 (or other multiplicator)
Hide youtube's info under your header and footer with an absolute position at top and bottom of iframe wrapper element. Height of header and footer could be calculated as: iframeHeight - (iframeWidth * (9 / 16))) / 2. If you want fullscreen than you should hide it outside screen visible zone and set overflow to hidden
In my case I use JS to destroy iframe after video is finished so user couldn't see youtube's offer with another videos
Also important note: since iOS 12.2 is replacing Youtube's player by their own, width and height calculation should be done in constructor(in case of React) because iOS player arrival cause page resize ->possible width&height recalculation-> video rerender -> video pause
code example jsfiddle.net/s6tp2xfm
A disadvantage of this solution is that it stretches image placeholder.
that's how it could look like with custom controls
