You can use the Dropbox App to do that for you, it will sync your media with your Dropbox automatically.
I think in this sync issue DRM is at fault. Sync between old iPods and iTunes worked that way because music was DRM'ed and they didn't want you to give your friend your 40GB iPod and let him copy all your music. It has been carried away too long, there should be two way sync.
This is a special pain in the ass when you have more than one Mac.
Ah! Definitely not using Dropbox app to do the syncing for me automatically. Again, too much magic for something too important. I can't be guaranteed that the Dropbox app maybe somehow loses authentication and silently stops syncing, or maybe I edit a photo on iPhone and its filename is unchanged in the filysystem and it doesn't get synced over, or anything similarly weird and technical goes wrong.
Maybe I'm being paranoid but all I want is a perfect and completely transparent guarantee that I have a complete snapshot of my most important files. I'm willing to do the little manual work for it.
I think in this sync issue DRM is at fault. Sync between old iPods and iTunes worked that way because music was DRM'ed and they didn't want you to give your friend your 40GB iPod and let him copy all your music. It has been carried away too long, there should be two way sync.
This is a special pain in the ass when you have more than one Mac.