Dropbox is already offering automated backup of photos and videos on their Android app.
They have now added this feature to their desktop app.
The app would upload photos and videos from external media like cameras and smartphones that you connect to your computer.
Dropbox spoke about this new functionality:
With the newest version for Mac or Windows, you can just plug your camera, phone, or SD card into your computer and with a few clicks of the mouse all your photos and videos are in your Dropbox! Automatic uploading from the desktop is designed to work perfectly with the Dropbox Android app. Your photos are copied from your camera to your Dropbox and uploaded, in full-quality and at their original size, to your private Camera Uploads folder. As your photos upload, you can access them from anywhere and move and share them as you see fit.
Dropbox is offering 3GB of extra storage to users who use this feature. 500MB on first automated upload. This is similar to how they rolled out this functionality on their mobile app.