It's one thing to allow an employer access to their own stuff. Whole different (ugly) ball of wax when outsiders want direct access, or even co-locating their own "stuff". Heck, even if you "kept it clean" by allowing them to bring in their own internet circuit, install their own equipment and infrastructure... you'll still have the headaches of them wanting physical access, which will seldom be at a convenient time for you.
Whether its at home or at work, you made the best choice. You can still be the upstanding citizen/employee by providing footage when requested.