<?php

$url1 = 'http://r...content-available-to-author-only...e.ru/video/d5a659aa519c7ee02b369ac858f06251';
$url2 = 'http://r...content-available-to-author-only...e.ru/play/embed/7027220?autoStart=true&bmstart=0&isFullTab=true&ref=window';

$urlmatch = '(?:video|play/embed)/(\w+)';
preg_match('~'.$urlmatch.'~', $url1, $match);
print_r($match);
preg_match('~'.$urlmatch.'~', $url2, $match);
print_r($match);