XF 2.0 Custom Field with Restrictions

[thunderup]

Is there any way to make a custom user field that is a text field only allow a specific set of data to be used once on the site?

For example, if I made a custom field for Youtube Accounts, it would only allow a specific youtube account to be entered on one user account on the forum... if put my youtube account field as "toodlez" nobody else could put "toodlez" for their youtube account field

 

[Paul B]

That would require custom development.