Starting August 1st, basic accounts' original source files will be stored for one week from the upload date, after which they will be removed.
This new one-week policy applies to all basic accounts' videos uploaded from this point onwards. For videos that were uploaded before this blog post, those original files will be available until August 1st, to give you some time to download them if you need to. After August 1st, those files will also be removed.
Well, according to them, “original file storage of every file for every user is a massive cost, and we have noticed that only a very small set of users actually ever download their own files”.