Here's an additional guide that may help you regain access (it covers more scenarios): https://goo.gl/q2Ijwz . Hope it helps!
@TeamYouTube Any chance of access to an account created by a former employee for company videos that's been dormant for 5yrs...? Recovery email unknown.
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Unfortunately, no longer have access to the recovery email, and no idea who would have set the security question... Not making this easy!
End of conversation
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