It is not currently possible to transfer recordings from Humax HDR-1000S/500S to an external USB or hard drive. The only known way to copy recording is to physically remove the hard drive from the receiver and connect it to a computer.
The hard drive is formatted in Linux ext3 and split into three partitions, the recording partition is not encrypted. Partition /dev/sda2 is used to store recordings.
The Humax HDR-1000S/500S will not allow you to play back any copied recordings from a USB, it will not recognise the hts files.
The hts files are encrypted, this applies both to SD and HD recordings, it is not possible to play the files on your PC.
If you know of any way to copy files or have any more information, please drop me a line.
See: Copying to USB on a Humax HDR 1000/1010/1100S