I’ve checked the code and it seems it tries to get thumbnails for playlist, but the if (preg_match($series_pattern, $body, $matches)) here evaluates to false (youtube.php):
/**
* Get the first video id from a video series
*
* @param string $src
*
* @return string
*/
function cmplz_youtube_get_video_id_from_series($src) {
$output = wp_remote_get($src);
$youtube_id = false;
if (isset($output['body'])) {
$body = $output['body'];
$body = stripcslashes($body);
$series_pattern = '/VIDEO_ID\': "([^#\&\?].*?)"/i';
if (preg_match($series_pattern, $body, $matches)) {
$youtube_id = $matches[1];
}
}
return $youtube_id;
}
This is an example for a playlist URL I’m trying:
https://youtube.com/watch?v=videoseries%3Flist%3DPLy2PCKGkKRVbpzEZG0iue9xSM9eMXqNmo%26enablejsapi%3D1
BTW, it might be possible to get the thumbnail from the playlist itself, without the need of getting the first video in it.
This code seems to work both for playlists and regular videos:
add_filter('cmplz_placeholder', 'filter_cmplz_placeholder', 10, 3);
function filter_cmplz_placeholder($new_src, $type, $src) {
switch ($type) {
case 'youtube':
$url = str_replace('/embed', '', $src);
$url_encoded = urlencode($url);
$response = wp_safe_remote_get('https://www.youtube.com/oembed?url=' . $url_encoded);
if (!is_wp_error($response)) {
$data = json_decode(wp_remote_retrieve_body($response));
$thumbnail_url = $data->thumbnail_url;
$new_src = $thumbnail_url;
}
break;
}
return $new_src;
}
