My DVD have till 12 midnight to be returned. If library is closed and I put DVD in book return outside library like 8pm will I be charged late fee? Does library have a way to see books or DVD were returned before midnight on day due?

It should renew unless there's a hold on it or you've renewed it the max allowed times. And yes, as long as it is in that drop box tonight, it will count towards today's date. (I know both through personal experience.)

You may want to try and renew online 1st. Not sure with dvds if it will work. If it doesnt, I would put it in the drop box and you can always call the next day. The librarians are very accommodating at that branch.