That clip is misleading and didn't show enough time, he was not acknowledging #68, the ref was looking at #70 the whole time as he was running onto the field and nodded at him. The ref was not paying attention to #68, maybe he should have, but it also the player's responsibility to get the ref's attention and make sure he is clear. The Lions tried some trickery, but not well thought out since whatever "surprise" would be spoiled once the ref announces to the entire stadium who is now eligible and walks over to the defensive captain tells him as well. If this was a hurry-up situation, maybe it has some merit, but the game clock isn't running, neither side is rushing to get aligned and everyone will be made aware of the situation and ample time to adjust.
The only reason this play worked in the first place was the Cowboys did not account for him because he was not reported to them as eligible, had he been they would have accounted for him. To the Cowboys, he was just an ineligible player down field.
It was announced over the stadium PA system and a Lion's player or Coach, ST Coach, should have caught that and adjusted accordingly.