import re


def check_url(url):
    """ Check if url is actually a valid YouTube link using regexp.

    :param url: string url that is to be checked by regexp
    :return: boolean True if the url matches the regexp (it is a valid YouTube page), otherwise False
    """
    youtube = re.compile(r'(https?://)?(w{3}\.)?(youtube.com/watch\?v=|youtu.be/).{11}')

    return True if youtube.match(url) else False