To add to #2, if you use backup software (or possibly a script?) that copies new files in real time (not sync...just copy) to a 2nd directory, then sync that 2nd directory with Dropbox, then you should be able to delete motion events from iCam without it affecting your Dropbox or 2nd directory. With that being said, you'd need to occasionally empty out the 2nd directory (which would be mirrored on Dropbox) so that you don't run out of space on your Dropbox account.