I'm having trouble retrieving the youtube video automatically, heres the code. The problem is the last part. download = urllib.request.urlopen(download_url).read()

    # Youtube video download script
    # 10n1z3d[at]w[dot]cn

    import urllib.request
    import sys

    print("\n--------------------------")
    print (" Youtube Video Downloader")
    print ("--------------------------\n")

    try:
            video_url = sys.argv[1]
    except:
            video_url = input('[+] Enter video URL: ')

    print("[+] Connecting...")
    try:
            if(video_url.endswith('&feature=related')):
                    video_id = video_url.split('www.youtube.com/watch?v=')[1].split('&feature=related')[0]
            elif(video_url.endswith('&feature=dir')):
                    video_id = video_url.split('www.youtube.com/watch?v=')[1].split('&feature=dir')[0]
            elif(video_url.endswith('&feature=fvst')):
                    video_id = video_url.split('www.youtube.com/watch?v=')[1].split('&feature=fvst')[0]
            elif(video_url.endswith('&feature=channel_page')):
                    video_id = video_url.split('www.youtube.com/watch?v=')[1].split('&feature=channel_page')[0]
            else:
                    video_id = video_url.split('www.youtube.com/watch?v=')[1]
    except:
            print("[-] Invalid URL.")
            exit(1)       
    print("[+] Parsing token...")
    try:
            url = str(urllib.request.urlopen('http://www.youtube.com/get_video_info?&video_id=' + video_id).read())
            token_value = url.split('video_id='+video_id+'&token=')[1].split('&thumbnail_url')[0]

            download_url = "http://www.youtube.com/get_video?video_id=" + video_id + "&t=" + token_value + "&fmt=18"
    except:
            url = str(urllib.request.urlopen('www.youtube.com/watch?v=' + video_id))
            exit(1)

    v_url=str(urllib.request.urlopen('http://'+video_url).read())   
    video_title = v_url.split('"rv.2.title": "')[1].split('", "rv.4.rating"')[0]
    if '"' in video_title:
            video_title = video_title.replace('"','"')
    elif '&' in video_title:
            video_title = video_title.replace('&','&')

    print("[+] Downloading " + '"' + video_title + '"...')
    try:
            print(download_url)
            file = open(video_title + '.mp4', 'wb')
            download = urllib.request.urlopen(download_url).read()
            print(download)
            for line in download:
                    file.write(line)
                    file.close()
    except:
            print("[-] Error downloading. Quitting.")
            exit(1)

    print("\n[+] Done. The video is saved to the current working directory(cwd).\n")