We're actually storing a single copy of every unique file. i.e. if you upload a completely identical, MD5 hash duplicate copy of something we already have stored, we'll just give you a pointer to that file. This way, we don't have to store every file, and we're not like iTunes Match (which actually requires licensing) because we're not giving you a master file (iTunes Match gives you a master file that plays at 256kbps, even if you upload the same song at 128Kbps -- they can do this through licensing; we can't give you a master 720p video file even if you upload a 360p version because we don't have those licenses). Legally, doing the MD5 hash duplicate technique was deemed legal after MP3Tunes' case (not referring to their entire case, just the part about the MD5 hash duplication) because it's just like any other method of compression.