That said... unless Dropbox has changed significantly since I last studied it -- which is quite possible -- I'm unaware of any facility for anyone other than an account owner to add files to it. I believe Dropbox is an outbound-only file sharing facility, say unlike FTP. So presumably the procedure would be what...
- I send the file to an admin somehow; email should work ok for 10 MB.
- Admin posts to Dropbox and sends me the public link.
- I test and then add the link to the updated forum post.
Not particularly fast turnaround, but yeah... that would work. It also has the very nice benefit of ensuring that the admins can keep the post alive and working if I and some private storage system I'm using fall off of the TOGoverse.