Authentication Lock Error/ Conflict

please investigate this error

We are fellow users, these are user forums, you're not talking to iTunes Support nor Apple on here.

I have a video showing the devise on my device list

Does the device show in the Find iPhone section of the account on http://www.icloud.com ? If not you are not logging into the account that it's locked to, and it's not the account that can re-activate it.

If you were the original purchaser of the iPad (i.e. it wasn’t bought used), you could try going to an Apple Store (make a Genius Bar appointment if you do) or try contacting iTunes Support online (http://www.apple.com/support/itunes/ww) and see if they can remove the iPad from the account - they are likely to want to see proof of ownership before they might help e.g. original receipt with the serial number on it

For the account that you are trying does the iPad show in the Find iPhone section of it on http://www.icloud.com ?

transaction with the apple reseller

By 'reseller' do you mean a store selling new devices, or a store reselling used devices ? If the latter they won't help as you weren't the original purchaser. If the former does the receipt contain the iPad's serial number ?

It shows where on the phone, do you mean in the Find iPhone app ?

its an official retailer but not the serial number it is 7 years old and so no physical receipt exists

Have you tried contacting the store to see if they can issue a duplicate receipt ? Without proof of ownership Support won't be able to do anything.