He's not talking about an actual canon. He's asking if Eternal's Ganbaride finisher is the real finisher for Eternal, and something just not made up, or added on.
As far as finishers, the three currently listed Ganbaride finishers he has are Eternal Never End, Hell Soldier Blade, and Dead Body Break. Now if there's one thing that Ganbaride is known for, it's not always getting rider attack names right, so one or more of those finishers could the same in appearance as one of his actual attacks, but I'm not sure since video footage of Eternal is sparse and Ganbaride footage is even sparser
edit: the Eternal Never End attack seems to be a variation of his 26 T2 Memory attack, Never Ending Hell