What does the drive say in terms of actual capacity and free capacity?
Have you tried looking for "hidden files"
Even if you do locate them, you might have a problem decoding them. Samsung, for example, encode the files using a key based on the TV's mother board so they can only be replayed on that TV - and if the board is changed, the files cannot be decoded. Sony, given their history of DRM, may do something similar.
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