If ds download would one one day morph into a file manager also… but you need to know where all these videos are stored in your iDevice, etc.
Seems to me if you want to backup your iPhone video/photo, you already have a copy Apple’s My Photo Stream in your PC or in iphoto, you can then auto sync that local folder to the NAS with cloud station.
The best way I can think of is to use Dropbox, because it allows you to send an iPhone video/photo to their cloud service (icloud too, but icloud can’t sync with synology’ cloud sync YET), you can then use cloud sync to sync the dropbox with your NAS, it’s not the direct way, but it’s painless. Get a free dropbox account, then install cloud sync on your nas and also install the dropbox free app. Then tap the video, upload (lower right corner) > more > save to dropbox > activate
if only one day sinology app would allow you to tap into the camera interface like dropbox’s…