If it's the deck I think it is, he may have assembled the deck himself using cards from several different decks - hence the "stolen cards" in the title.
Using Google, I managed to learn something important - there's more than one version of Lennart's deck. An earlier version used cards from nothing but casino decks, most if not all of which having been canceled with cut or rounded corners. The current version uses absolutely no casino cards and contains not just known USPC decks but also more obscure ones with beer ads and children's cartoons on them. I witnessed a video of a performance where the deck had two pairs of Jerry's Nugget cards, two in each color - they were the "magic" cards of the trick, the prediction and the spectator's.
It seems that rather than printing individual cards from different decks, the decks are constructed by "stolen cards" - they buy decks to mix with other cards to construct the stolen decks. This means that different performances may have different card backs in use. This might make identification difficult.
Perhaps you can pause the video at the point where the card of interest is visible? Perhaps it even appears in ?