function add_video_load( $content ) { if( is_feed() || is_preview() || ( function_exists( 'is_mobile' ) && is_mobile() ) ) return $content; if ( false !== strpos( $content, 'data-src' ) ) return $content; $placeholder_image = ('data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs='); $content = preg_replace( '#<iframe([^>]+?)src=[\'"]?([^\'"\s>]+)[\'"]?([^>]*)>#', sprintf( '<iframe${1}src="%s" data-src="${2}"${3}>', $placeholder_image ), $content ); return $content; } add_filter( 'the_content', 'add_video_load' );