Ouch. When your app is so slow that it throws the screen-cast presenter off his game, it's not premature optimisation to speed it up a bit.
Or you could, at least, edit the wait out of the video,
No kidding - no chance I would use that if, for each email I opened, I would have to wait an additional 2-4 seconds for it to do its thing. And not a very high quality sounding video either - had to turn my volume up to more than half way to hear it and, when I did, it has a poor sound to the voice with a lot of hum.