Likewise, video clips with a resolution over 1920x1080 won't be uploaded to the app, and there's no way to manually upload anything yourself?
Any screenshots and clips you capture once you've enabled this new feature will automatically be stored on the PlayStation app for 14 days.You can then view and share them through an app of your choosing, even if you aren't hooked up to WiFi (just keep an eye on your data usage so you don't get an overage charge.) You don't even need a PlayStation Plus subscription to take advantage of the feature, though that could change once it gets a full release.
Plus, if you accidentally delete a screenshot or clip by mistake, it'll still be viewable and shareable via the PlayStation app as a backup!