If you read the first letters of each word in his speech, it spells MAGAlomaniac! I wouldn't be surprised to learn that the DNC camp has better strategists who came to the same conclusion, or at least saw it as a probability / opportunity. Trump, despite his odd characteristics, is surprisingly predictable. What I find unlikely is that this goes back any further than, say, early 2015. (Shockingly, Trump's announcement to run for president was in June 2015. Holy hell, has it really been that long?) Especially your suggestion that she orchestrated the correspondent's dinner touchdown is just too much of a stretch for me.
My perspective: There was zero to lose by trying the gambit. I mean, goading Donald Trump generally results in a lawsuit at worst, and suing the president for slander is exactly the sort of thing that would make Trump effectively go away forever. There was plenty to gain: if you can get him to charge, it will be entirely on the Republicans to stop the stampede. So the costs-benefits analysis is this: do you let the press writers to write a few throwaway jabs about Trump and birtherism? Or do you make a few phone calls, say "hey, I've got an idea" and then get those same writers to really get under his skin? The only remaining question is whether you think Hillary Clinton is playing that many moves ahead. I would argue that you're stupid if you think she isn't. I'm not betting that this was a known outcome that she was banking on; I'm betting that this is a possibility that she's been cultivating into a probability.
The Clintons have been working the angles in full view of the public for decades. Donald Trump is used to back-office deals, and posing for cameras. Hillary Clinton is already putting chess pieces onto a board that Donald Trump doesn't even see yet, because he's still focusing about that bishop that just took his pawn in move 5 on this chessboard.