Check if a Post Has Embedded Content

The following snippet lets you check whether a specific post has embedded content. It works inside the loop using the post ID. Alternatively, you can pass any ID to check if that post contains embedded content.

<?php

function has_embed( $post_id = false ) {
	if( !$post_id ) $post_id = get_the_ID();
	else $post_id = absint( $post_id );
	if( !$post_id ) return false;

	$post_meta = get_post_custom_keys( $post_id );
	$post_meta = array_map( 'trim' , $post_meta );

	foreach( $post_meta as $meta ) {
		if( '_oembed' != substr( $meta , 0 , 7 ) )
			continue;
		return true;
	}
	return false;
}

Usage:

if( has_embed() ) {
   // do whatever
}

For more on embedded content, see Improving Loading Time of Embedded Videos.