I like using Resilio as part of my backup strategy as it is 'close' and something I'm actually using. Something he didn't show is that Resilio can keep previous copies of files (I think that are deleted) and holds them temporarily in a temp folder on the remote machines. I'm not sure about how it decides what the retention policy is or what may or not be excluded from this. As far as the Backup, what I did start doing about a year ago is I have sync on a couple Pi's that one operates as my main NAS and there's a remote one that syncs data. The new addition was the desktop resilio sync i installed (usually just let the NAS grind away in the background) and had it point the directories to an external drive. Once a month or so, I'll hook that drive up (usually in fireproof safe) and let it sync to the Sync 'cloud' and update. What's slick is that it's pretty automated once setup and I just plug in the drive and run Resilio and it grinds away.

It works with any files. The program shouldn't matter. The Resilio app sometimes 'complains' that a file is locked if you have it open on your device that has resilio running. But, once you close the program and let the file sit for a bit, resilio should grab it and replicate it elsewhere. Slick thing about Resilio that isn't documented much is that it should likely do delta file updates. If you have a huge file that's already synced around but edit it and make some small changes, Resilio should scan the file and only use the internet connection to sync the changes vs resending the whole file again.