The My Book user defined to the WD Live Plus has write privileges. I can delete files via the file manager dialog, however, I cannot resume a video when the WD Live has been powered off and back on. I can resume if the unit is still powered up. It does not matter if I access the video from the medial player or as a network share. It appears that the WD is not updating the .wd_tv files.
WD Live Plus - Firmware - 1:06.16_B
My Book Live - Firmware - 02.11.09-053