def _build_youtube_dl_coprocessor(cls, session: AppSession, proxy_port: int):
        '''Build youtube-dl coprocessor.'''

        # Test early for executable
        wpull.processor.coprocessor.youtubedl.get_version(session.args.youtube_dl_exe)

        coprocessor = session.factory.new(
            'YoutubeDlCoprocessor',
            session.args.youtube_dl_exe,
            (session.args.proxy_server_address, proxy_port),
            root_path=session.args.directory_prefix,
            user_agent=session.args.user_agent or session.default_user_agent,
            warc_recorder=session.factory.get('WARCRecorder'),
            inet_family=session.args.inet_family,
            # Proxy will always present a invalid MITM cert
            #check_certificate=session.args.check_certificate
            check_certificate=False
        )

        return coprocessor
Build youtube-dl coprocessor.