A WordPress plugin for embedding content from vine

vine-oembed.php

<?php
/*
 Plugin Name: Vine oEmbed
 Plugin URI: http://interconnectit.com
 Description: Registers an oEmbed handler for Vine URLs
 Version: 1.0
 Author: Robert O'Rourke
 Author URI: http://interconnectit.com
*/

if ( ! class_exists( 'vine_oembed' ) ) {

	class vine_oembed {

		// used to match embeddable URL
		public $regex = '#https?://vine.co/v/([^/]*)(/embed/(simple|postcard)(\?audio=1)?)?#i';

		public function __construct() {

			add_action( 'init', array( $this, 'init' ) );

			// modifies the js tag to have async and charset attributes as per vine embed code
			add_filter( 'script_loader_src', array( $this, 'async_script_tag' ), 10, 2 );

			// remove the <p> tags from iframe
			add_filter( 'the_content', array( $this, 'unpee' ), 20 );

		}

		public function init() {

			wp_embed_register_handler( 'vine', $this->regex, array( $this, 'handler' ) );

		}

		// returns the iframe
		public function handler( $matches, $attr, $url, $rawattr ) {

			// default type
			$type = '/embed/simple';

			if ( isset( $matches[2] ) )
				$type = $matches[2];

			$embed = sprintf(
				'<iframe class="vine-embed" src="https://vine.co/v/%1$s%2$s" width="600" height="600" frameborder="0"></iframe>',
				esc_attr( $matches[1] ),
				$type
				);

			// vine async embed js
			if ( ! is_admin() )
				wp_enqueue_script( 'vine-embed', '//platform.vine.co/static/scripts/embed.js' );

			return apply_filters( 'embed_vine', $embed, $matches, $attr, $url, $rawattr );
		}

		// adds filter to esc_url if we're rendering vine embed script
		public function async_script_tag( $src, $handle ) {
			if ( $handle === 'vine-embed' )
				add_filter( 'clean_url', array( $this, 'mod_script_tag' ), 11, 1 );
			return $src;
		}

		// adds attributes to vine embed script tag
		public function mod_script_tag( $src ) {
			remove_filter( 'clean_url', array( $this, 'mod_script_tag' ), 11 );
			return "{$src}' async charset='utf-8";
		}

		// removes p tags from iframes
		public function unpee( $content ) {
			$content = preg_replace( '/<p>(<a [^>]*?><iframe [^>]*?><\\/iframe><\\/a>|<iframe [^>]*?><\\/iframe>){1}<\\/p>/s', '<div class="embed-iframe">$1</div>', $content );
			return $content;
		}

	}

	$vine_oembed = new vine_oembed();

}

@sanchothefat good snippet, which can be usefull for add wp 4.0 fallback support.
But I think it will be better to use entry-content-asset instead of embed-iframe class, because Wordpress by default wraps all oembeded iframes in entry-content-asset class..