That's what it sounds like. You can't play live from HDD, so need to reinstall and potentially remove something else from your internal HDD, but you won't need to redownload again. It means you don't have complete access at all times to your whole library, unlike play from external device as per XB1, but do have access to old, backed-up games without a whole download again. Minimum reinstall time will be time to copy the game data from external to internal. Worst case, 50 ish GBs (game size) over USB3. Something like a few minutes.