How do I access my HD connected through USB to the WD Live TV player through my PC?

Hello,

You just have to map the drive on the computer.

Follow the instructions that you will find on the link below.

Mapping a Personal Cloud drive or WD NAS drive on a Windows PC 

Also check page # 31 of the user’s manual

http://www.wdc.com/wdproducts/library/UM/ENG/4779-705062.pdf