the time between clicks is random, it is a Dell laptop i borrowed from my friend i hope i didnt break it. i 70% sure it comes from the center, i dont know the model number.
Make sure that there's nothing in the DVD tray first and observe it again. The clicking sound might be coming from either the fan or the HDD of the laptop give that the HDD is not a Solid state drive. With the fan there might be some wire hitting the fan that might cause that clicking sound.