Hi @nytix – Regarding the grey bar, I think this has already been reported in Trac:
https://core.trac.www.ads-software.com/ticket/40522
You can add screenshots and details of your case there if you like. There’s also a patch attached, which removes one line in the stylesheet – you could try it if you want, and see if it fixes your issue.
https://core.trac.www.ads-software.com/attachment/ticket/40522/40522.patch
Regarding no auto-play on smaller screens, this is coming from a setting in Core, which restricts auto-play on video headers to screens greater than 900 by 500px. It’s found in the file /wp-includes/theme.php
in this function:
/**
* Retrieve header video settings.
*
* @since 4.7.0
*
* @return array
*/
function get_header_video_settings() {
$header = get_custom_header();
$video_url = get_header_video_url();
$video_type = wp_check_filetype( $video_url, wp_get_mime_types() );
$settings = array(
'mimeType' => '',
'posterUrl' => get_header_image(),
'videoUrl' => $video_url,
'width' => absint( $header->width ),
'height' => absint( $header->height ),
'minWidth' => 900,
'minHeight' => 500,
'l10n' => array(
'pause' => __( 'Pause' ),
'play' => __( 'Play' ),
'pauseSpeak' => __( 'Video is paused.'),
'playSpeak' => __( 'Video is playing.'),
),
);
if ( preg_match( '#^https?://(?:www\.)?(?:youtube\.com/watch|youtu\.be/)#', $video_url ) ) {
$settings['mimeType'] = 'video/x-youtube';
} elseif ( ! empty( $video_type['type'] ) ) {
$settings['mimeType'] = $video_type['type'];
}
return apply_filters( 'header_video_settings', $settings );
}
Themes can override this setting, but Twenty Seventeen does not. To make a change in this functionality on your site, you could create a custom function and add it either to a child theme or functionality plugin.