message: alt is not valid on video element
diff: @@ -215,7 +215,7 @@ export default class MVideoBody extends React.PureComponent<IProps, IState> {
  }
  return (
  <span className="mx_MVideoBody">
  - <video className="mx_MVideoBody" src={contentUrl} alt={content.body}
  + <video className="mx_MVideoBody" src={contentUrl} title={content.body}
  controls preload={preload} muted={autoplay} autoPlay={autoplay}
  height={height} width={width} poster={poster} onPlay={this._videoOnPlay.bind(this)}>
  </video>
  