When I press the Media button, next to the recordings listing my 512gig HDR2000T shows a small pie chart for HDD usage as 25% light green and 25% dark green with 50% light grey. I get that the light grey space is free, but I don't understand the other two colours. I originally thought the light green was system files, but it seems not as I certainly have over a quarter of the drive filled with content. Both greens seem to increase in size. Can anyone enlighten me?