function dozent_video_sources( $source = null ) {
		$sources = apply_filters( 'dozent_video_sources', [
			'html5'        => __( 'HTML5 (.mp4)', 'dozent' ),
			'external_url' => __( 'External URL', 'dozent' ),
			'youtube'      => __( 'YouTube', 'dozent' ),
			'vimeo'        => __( 'Vimeo', 'dozent' ),
			'embedded'     => __( 'Embedded', 'dozent' ),
		] );

		if ( $source ) {
			return dozent_array_get( $source, $sources );
		}

		return $sources;
	}