<?php
function wpdevhq_get_video(){
	global $wpdevhq_videos;
	$post_id = get_the_ID();

	if( empty( $wpdevhq_videos ) ) $wpdevhq_videos = array();
	if( isset($wpdevhq_videos[$post_id]) ) return $wpdevhq_videos[$post_id];

	$content = get_the_content();
	$content = apply_filters( 'the_content', $content );
	$content = str_replace( ']]>', ']]>', $content );
	$content = trim($content);

	// Is the first line a video?
	list($line, $content) = explode("\n", $content, 2);

	if ( preg_match('/\<\s*(iframe|object|embed)/i', $line) ) {
		$wpdevhq_videos[$post_id] = strip_tags($line, '<iframe><object><embed>');
	}
	else {
		$wpdevhq_videos[$post_id] = false;
	}

	return $wpdevhq_videos[$post_id];
}

/**
 * Removes the video from the page
 *
 * @param $content
 *
 * @return mixed
 */
function wpdevhq_filter_video($content){
	list($line, $rest) = explode("\n", $content, 2);
	if ( preg_match('/\<\s*(iframe|object|embed)/i', $line) ) return $rest;
	else return $content;
}

/**
 * You can then return the extracted video via
 */
echo wpdevhq_get_video()
?>