Filming elevators at hotels are quite hard unless you stayed at their hotels while go shopping at malls while hunting for some elevators (sometimes, security doesn't like to be caught in the video during elevator filming if the security enter the elevator at the malls). Here are some tips how to film it!
Hotels[]
Most low end till high end hotels have an elevator. Either modern elevators, classic elevators or even rare elevators (some case, some historical hotels like E&O Hotel in Penang have vintage elevator). Before you film it, make sure you ask permission to film an elevator at their property. If they accept your permission, you can film it without any risk. If not, you can get busted for being trespassed to their property. Unless you stayed at their hotel for at least 1 night.
If there is a service elevator at the hotel you stayed or planned to film, just avoid it unless you brave enough, try at your own risk (best time to film: late at night). Make sure it is easy access.
Malls[]
If you planned to film at any malls, please avoid the service elevators. Unless you have special permission from security or person in charge to get in and film it.
For public elevators, you're able to film it without having trouble with security. If the security enter the elevator, lower down the camera quickly and act like you're playing games because not to show their face caught on your elevator video.