pinafore/routes/_components/VideoDialog.html

<div class="video-dialog-wrapper">
  <div class="close-video-button-wrapper">
    <button class="close-video-button" aria-label="Close dialog" on:click="onCloseButtonClicked()">
      <span aria-hidden="true">&times;</span>
    </button>
  </div>
  <video poster="{{poster}}"
         src="{{src}}"
         width="{{width}}"
         height="{{height}}"
         controls
  />
</div>
<style>
  :global(.video-dialog) {
    position: fixed;
    top: 50%;
    transform: translate(0, -50%);
    background: #000;
    padding: 0;
    border: 3px solid var(--main-border);
  }
  :global(.video-dialog-wrapper) {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    max-width: calc(100vw - 40px);
  }
  :global(.video-dialog video) {
    max-width: 100%;
  }
  .close-video-button-wrapper {
    text-align: right;
    width: 100%;
    background: var(--nav-bg)
  }
  .close-video-button {
    margin: 0 0 2px;
    padding: 0;
    background: none;
    border: none;
  }
  .close-video-button span {
    padding: 0 15px;
    font-size: 48px;
    color: var(--button-primary-text);
  }
  :global(dialog.video-dialog::backdrop) {
    background: rgba(51, 51, 51, 0.8);
  }
  :global(dialog.video-dialog + .backdrop) {
    background: rgba(51, 51, 51, 0.8);
  }
</style>
<script>

  import { importDialogPolyfill } from '../_utils/asyncModules'

  export default {
    oncreate() {
      // TODO: this hack is for Edge 16, which makes the modal too wide
      if (typeof setImmediate === 'function' && navigator.userAgent.match(/Edge/)) {
        this.get('dialog').style.width = `${this.get('width')}px`
      }
      this.registration = this.register()
    },
    methods: {
      async register() {
        if (typeof HTMLDialogElement === 'undefined') {
          let dialogPolyfill = await importDialogPolyfill()
          dialogPolyfill.registerDialog(this.get('dialog'))
        }
      },
      async showModal() {
        await this.registration
        this.get('dialog').showModal()
      },
      onCloseButtonClicked() {
        this.get('dialog').close()
        document.body.removeChild(this.get('dialog'))
      }
    }
  }
</script>