My primary use case for Dropbox, actually, is getting videos onto my iPhone. You can't simply drag and drop a video file into the phone as a mass storage device. With ITunes, the sync feature purportedly sync the video to the device, and consumes space accordingly, but there's no way to access the video on the device. It's actually way faster for me to upload a video to Dropbox from my computer, and download the video on the Dropbox app into my photos. The video quality is excellent, too!