So what if when Zoom grabbed Jay he somehow dragged him to the past due to the vortex being all wibbly wobbly and the Jay with the mask is this Jay's future and what he was actually trying to tap is a warning to Barry to tell Jay not to stand so close to the vortex?
I'm so tempted to think that, as well, but it doesn't work. If Zoom travels to the past to lock future Jay in a cell, then Zoom would've already known the outcome of everything that happened in this episode and would've killed Killer Frost the instant he arrived, preventing anyone from making their escape.
If the man in the mask is Jay, he's either some other form of Jay (clone or whatnot) or he was perhaps thrown into the past by himself, without zoom.
Unless Zoom wanted everyone to escape.
But still, why exactly choose such a complicated and situational message as the very first thing you say when you know you can be interrupted at any moment? And why just give up when people don't understand what you mean after 1 word? It would seem more logical to me that the message was supposed to be Zoom's identity (that is the most important thing, after all - key to finding him, stopping him, etc), and the man got frustrated because Barry was thinking in completely the wrong direction.
Also, didn't someone in here say that the tapping in last week's episode was morse code for 'Zoom is'? Possibly more of an easter egg, considering this ep went out of its way to say he wasn't using Morse Code, but that would seem to point to the fact that the man in the mask is the key to Zoom's identity.
By the way, Jesse and helmet-Jay not figuring out how to communicate for 5 months while they were there alone with each other makes no sense for the smartest person on two Earths even if the person she's stuck with is Jay, the dunce who stood too close to the vortex.
Doesn't matter how smart you are if you just give up. She'd written his tapping off as totally meaningless.