The Flash on episode 15 the man in the mask was continuously tapping on the glass. The clever Flash figured out what type of code he was tapping and it ended up as a 5 by 5 tap code. The man was repeating the letters" J A Y" and when Berry said "Jay? As in at Gerrick. He is fine but he is on my Earth." The man started banging his head, indicating that he might be Jay or Jay was bad. But what ever it was it hit a soft spot on him, he was emotionally upset.
Now to the hints first up is Jessie.
When Dr. Wells was talking to Jesse he said "My Jess you have been always been so quick." That made me think she could be the new female speedster named Jesse Quick.
Next up is the identity of Zoom.
When Jay was explaining to Kaitlin on how he 'lost' his speed he said "I was obsessed with speed. What I had wasn't enough, so I tried to make myself some speed." Then Dr. Wells when he was describing Zoom to Berry he said " Zoom is obsessed with speed, No one can stop him." So my best bet is that Zoom is Jay cause it all leads up to him.