Youtube parsing functions, this are brute force methods to get youtube video ID from URL.

gistfile1.php

function get_youtube_id( $youtube_url ) {
    $url = parse_url($youtube_url);

    if( $url['host'] !== 'youtube.com' &&
        $url['host'] !== 'www.youtube.com'&&
        $url['host'] !== 'youtu.be'&&
        $url['host'] !== 'www.youtu.be')
        return '';

    if( $url['host'] === 'youtube.com' || $url['host'] === 'www.youtube.com' ) :
        parse_str(parse_url($youtube_url, PHP_URL_QUERY), $query_string);
        return $query_string["v"];
    endif;

    $youtube_id = substr( $url['path'], 1 );
    if( strpos( $youtube_id, '/' ) )
        $youtube_id = substr( $youtube_id, 0, strpos( $youtube_id, '/' ) );

    return $youtube_id;
}

function get_video_image($embed) {
    //Each YouTube video has 4 generated images. They are predictably formatted as follows:
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/0.jpg
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/1.jpg
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/2.jpg
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/3.jpg
    //The first one in the list is a full size image and others are thumbnail images. The default thumbnail image (ie. one of 1.jpg, 2.jpg, 3.jpg) is:
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/default.jpg
    //For the high quality version of the thumbnail use a url similar to this:
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/hqdefault.jpg
    //There is also a medium quality version of the thumbnail, using a url similar to the HQ:
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/mqdefault.jpg
    //For the maximum resolution version of the thumbnail use a url similar to this:
    //http://img.youtube.com/vi/<insert-youtube-video-id-here>/maxresdefault.jpg
    

    // This gets the default thumbnail image
    $video_id = get_youtube_id($embed);
    $video_thumb = "http://img.youtube.com/vi/" . $video_id . "/0.jpg";
    return $video_thumb;
}