3. Use the "can't access your account?" link there with the email username of the Google account you closed, and-
4. Go through the options until you come to a Recovery Page which asks a whole bunch of security questions which you need to answer and send the form in with.
THIS is then considered (I gather) by Google staff who either reopen the Google account or not. Most users who were successful with this were kind enough to report back and yes- their YouTube channels were still attached, albeit minus videos. This became the only way to recover some of the YouTubes which were closed post-September 2011.
As stated- I would be very happy for you to try and let ME know if you can go through with this as I was not able to.