You do not have to move it back to watch. You just can't record to it.
Did you read my post all the way? I said in case the ext has issues. Im coming from Comcast DVR's that had external HDD support, but some did not do well playing HD video and experienced breakup.
Now, while I believe that all usb drives will work with the 622, that does not mean all will WORK perfectly with playback. Will believe it when I see it.
So, its good IMHO because if the drive I buy acts up, I can use it strictly for storage and move the video to the 622 when Im ready to watch it.