WD My Book DVD Expander 1TB does work with DCT6416 III
Just spent an incredibly frustrating 2 days with eastlink tech support trying to get a DVD expander hard drive working. Was told the (Shaw) IOMega from Best Buy was incompatible and needed to get the WD By Book DVD Expander. Took 6 hours on the ferry to go back to Best Buy in Vancouver to get the WD drive. Only to find that it too did not work. Tech support did not call back, then hung up on me, but finally another tried to download an upgrade to the DCT firmware (no idea what version). He said to try again after 30 minutes to see if the "hard drive needs to be formatted" message appears - IT DIDN"T.
So searched the web and found an old post that suggested to NOT POWER OFF THE DVR BEFORE PLUGGING IN THE EXPANDER. and then it worked!!!!! Up popped the message asking to format the Expander drive and now my 80% full suddenly became 0% full. Now going to try recording to make sure it really works doing that.