I would like to know if Cloudflare backs up the video that is uploaded to Cloudflare Stream and how often the videos will be backed up. I notice that Cloudflare compares itself with other typical cloud providers on the Stream product. Yet, as a developer, if I use other cloud providers, I can do many things to ensure my files will not get lost because of disruptions.
I am afraid not?, you cannot download the original uploaded file later - same as YouTube, only MP4 and compressed/optimized 
Furthermore, for “backup”, I’d suggest some storage server or archive, just in case, for the worst possible scenario, and not just Cloudflare thing.
coughR2cough
10 GB / month free forever. Not part of Stream, but it might fit the bill.