Inserting a background image in a video. How to do it?

Question

css

I would like to know how this can be done?
I found something similar here: https://jsfiddle.net/shakalaka/u2fym0he/
I tried to do this:

<div class="video-player">
<video src="https://upload.wikimedia.org/wikipedia/commons/transcoded/9/95/Bits_%26_Pieces_-_BP374_-_Test_flight_of_Pescara%27s_helicopter_-_1922_-_EYE_FLM7760_-_OB105716.ogv/Bits_%26_Pieces_-_BP374_-_Test_flight_of_Pescara%27s_helicopter_-_1922_-_EYE_FLM7760_-_OB105716.ogv.480p.vp9.webm"  poster= url("//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Bits_%26_Pieces_-_BP374_-_Test_flight_of_Pescara%27s_helicopter_-_1922_-_EYE_FLM7760_-_OB105716.ogv/250px--Bits_%26_Pieces_-_BP374_-_Test_flight_of_Pescara%27s_helicopter_-_1922_-_EYE_FLM7760_-_OB105716.ogv.jpg") style="width: 250px; height: 250px; background-size: cover;" title="Воспроизвести медиафайл" controls="" preload="none" autoplay="">
            </div>

But the background image just shines with white... Tell me, please, what am I doing wrong?