I lease a property and have exclusive use of such ,is it legal for the land lord to install video cameras inside one of those building I lease example a barn. I live in Maryland

You live in an apartment complex, they have cameras all around the outside, and often wash rooms, game rooms and so on.

I am not sure it is illegal, remember it is not a matter of being legal, it is an issue is there a law against it. This may also be an issue that just depends on your states law. Was there a camera there before you moved in. why is he doing this ?

Landlord "cams" are the coming thing and they are being mandated by the landlord's insurance company... why would you object?