This is a known issue right now. It is noted in the release notes that come along with each release in Test Flight.
When the large video preview is being used, only the top middle 3rd of the area responds to inputs. Swiping and tapping both work going up and down in size. As long as you use a nice long top to bottom swipe, you'll be fine!
It is functional for now. We hate it too but need to get the other features up and going.