I have done an iOS App Preview (Video) using iPhone 6 and Quicktime in Yosemite, but I cannot upload it for iPhone 6+ in iTunes Connect, and I don't have an iPhone 6+ Device.
Is there a way to make an App Preview (Video) for iPhone 6+ without the device ?
I have found a good solution!
In Keynote app, I changed the document size to be the same as iPhone 6+ size and imported the iPhone 6 video and resizes it. I have resived the video to fit the document and exported it as a video. That's it!
It is not a perfect solution, but it is good.