*::-webkit-media-controls-panel {
  display: none!important;
  -webkit-appearance: none;
}

/* Old shadow dom for play button */

*::-webkit-media-controls-play-button {
  display: none!important;
  -webkit-appearance: none;
}

/* New shadow dom for play button */

/* This one works! */

*::-webkit-media-controls-start-playback-button {
  display: none!important;
  -webkit-appearance: none;
}