Apple iOS runs each app in a sandbox, so in general, no app can see data from any other app. Enhanced security and privacy on iOS over android does come at a cost of data interchange. This design decision also enhances performance and saves battery life since every app isnxe2x80x99t trolling all the others for updates or plundering data it can then upload in efforts to track everything you do and store on your device.
That being said, there are several common file storage API on iOS. If every app you use did store the video/image/data in a common place, therexe2x80x99s no technical reason why you couldnxe2x80x99t have the same unified view.
In practice, youxe2x80x99ll need to manually curate or save off media you want on a case by case basis since most xe2x80x9cfreexe2x80x9d apps like Instagram, Snapchat, Facebook have business models that make sharing content against their best interest. Since consumers are the product instead of the customer of those apps, I donxe2x80x99t foresee huge or quick adoption of common storage on iOS anytime soon - even with iOS 11 making it far easier to use the xe2x80x9cgeneric searchable file systemxe2x80x9d idiom you mention that common on computers and android os.