Adobe's standard "Page" (s.pageName) variable is only stored on Page Views... it's removed from all Clicks/Actions/etc. (Even though you see s.pageName on your tracking calls, they are removed during processing... Adobe uses the existence of s.pageName and the backend URL value to determine if something is a page view.... so if you try and force the value using processing rules you will actually inflate your page views metric - I discovered that while mapping mobile app values)
This is why most implementations include a custom prop or eVar to hold the Page Name value (a lot of us use eVar so that we have 255 character limit, as opposed to prop's 100 character limit), and it's included on all page views and actions.
This is why you can't correlate your standard Page Name dimension to your video data, since none of those are triggering page views.