fuccaneer The comment you are referring to was misleading. The regular files that you download are the exact same files that SLR uses for streaming. These files are all variable bitrate¹ while the "original" quality ones can be variable or constant bitrate depending on what the studio supplied.
It would be an enormous waste of resources for SLR to be encoding separate versions for streaming and downloading given the number of scenes they have to deal with. For every scene they already have to encode h264 and h265 versions for like 5 different resolutions.
¹ In reality the video bitstream of these files is much closer to constant bitrate than variable bitrate.