This raises an interesting question on just how exactly the card should vanish...should the vanish be "implied" magic i.e. there were 5, now there are 4 therefore your card has vanished? Or should the vanish have it's own "moment" - use of the tent vanish, the rub a dub or some other contrivance? Which is more powerful in the eyes of an audience?
I think there is a strong case to be made for giving the vanish it's own moment; creating conviction in the minds of the audience that their card really is there. For the past year or so I have been doing the Biddle trick with a "lie detector" presentation, calling out the names of each card as I count through them faces toward myself (miscalling so they hear the selected card of course) and correctly narrowing it down to their card. Then it is reversed in the packet which is then flase counted again showing 4(?) X cards and a face down card - logically the selection. The face down card vanishes courtesy of an Elmsley and turns up in the pack.
At each stage there is strong conviction that YES the card really is in there, but I felt that the vanish never really got the reaction it deserved. Last time I performed it I handed the deck to a second spectator and the "5" card packet to the first spectator so that the vanish happened in their hands - much, much stronger reaction. Food for thought anyway...
The real issue as far as I'm concerned is how to get to the biddle steal position in the routine. The posted video is a classic example of the lack of consideration this phase usually gets; it's pretty weak. "I cut the deck a few times and your card is in these 5". What?
Tidying this phase up is definitely a worthwhile use of your time.