I've taken a look at the channel in question and I'm sorry to say it is not possible for you to find the email address which created the account or for you to "shut it down" without a court order.
This is a pre-2014 account without a confirmed name, and with maximum privacy settings enabled which hide their name and their email.
You can't find out who started the channel but you can try to close it down, by flagging their videos if they violate YouTube community guidelines. Unfortunately in your specific case this seems to be an act of whistleblowing and doesn't seem to violate and of the rules.
Your only option is to take the individual to court and sue for some form of defamation, and as part of that have the court force them to take it down.