I needed a file I deleted a month or so ago, for my clinical class. It was of a session with a client, but I decided not to use it and, so, I deleted it. After all, it was 3 GB. It's just that now, I wanted to do a "before and after" thing. (The client had done a tremendous amount of good work.)
I looked in Time Machine. It was not there. Maybe TM cleaned things up. Maybe I have something set to delete files so the backup drive doesn't fill up too fast. I tried Crashplan. I put in the search string ".MP4." It found some, but not the one I needed. Bummer!! Oh. Wait. "Display deleted files." Check. Try again. BINGO! Brilliant.
I have CrashPlan Family Unlimited. Like getting a "replacement" policy for fire insurance, when you need it you'll be glad you did.