(Long post warning...)
Eric, thank for the response, but on the iPad, there isn't a sync slider. Under the iCloud menu, there is "Photos >on", under which there area two sliders that may relate to your answer: "iCloud Photo Library", and "Upload to My Photo Stream". When I slide off the first, it popped up a "Download All Photos & Videos" dialog with choices to: Remove from iPad, Download Photos & Videos, or cancel. My guess is, "Remove from iPad", to be the best choice, but the dialog only refers to photos and videos that are not fully downloaded, to be removed from the iPad. Would it still leave those that are fully downloaded? The second choice which is to download all photos/videos would defeat the purpose.
The other slider "Upload to My PS (Photo Stream)" when selected, pops up a dialog stating "Turning off PS, will delete all PS from your iPad". I tried it, then re-enable it again, but not much was gained, and the latest video is still not uploaded.
By the way, when I try to sign out of iCloud, a "Delete Account" dialog came up. I decided not to proceed, since I do not want to delete my iCloud account.