[Fizzlemizz]

You don't need

AMD_TabOnCharacterFrame:OnLoad(AMD_OnLoad(self));

but if you wanted to add a method to the frame you could use a Mixin or

function AMD_TabOnCharacterFrame:OnLoad()
    print(self:GetName(), "I'm loaded now!")
end
 
AMD_TabOnCharacterFrame:OnLoad()

Adding an OnLoad function in lua to AMD_TabOnCharacterFrame doesn't really make sense in your case as it's already been loaded so, just using:

print(AMD_TabOnCharacterFrame:GetName(), "I'm loaded now!")

instead of adding the function and making the call would do the same.