Re: Sharing a 3.5 gig file
Me, I try to keep everything digital. The physical will only take up space and I'll lose it anyway.
Really depends on how good with technology your family is. I find Google Drive faster than Dropbox and has more space (even for uploading).
Plus how do you expect the movie to be watched? Obviously if it's going into a DVD player you'd want to burn it on to a DVD, make sure it plays, and mail it out. (I think how it will be watched will tell you what you need to do. A digital copy is no use if it's going into a DVD player unless it has a USB slot).
Also, DVDs are not infallible, they won't last forever, and you'll need to put them in cases before mailing out.