I've got this answer from Apple at submitting a new version that includes a preview video where all the interaction is shown within a device.
The text of rejection is this:
Guideline 2.3.4 - Performance - Accurate Metadata
Your app preview includes content that does not sufficiently reflect the app in use. Specifically, your preview:
Includes device images and/or device frames.
Now, at reviewing the guidelines, it mostly refers to the video not being "faked" or show behind the scenes or etc which make perfect sense, but, they do not state that the video cannot be contained within a device frame. It's not stated anywhere.
I've seen videos with framed showcases of the apps, and I wonder if any of you has a video like this that would have been accepted.
I'm re creating the video without the frames but it might compromise either timing or message... any help here would be great.