Many volunteers who originally designed or worked on the IBM 1401 helped the Computer History Museum to make this exhibit come true. There was a manual card puncher device you could punch any message on blank punch cards (the couple on the video tries to figure it out). There are scheduled times when the machine is operated and I found extremely long integers printed out in the trash bin. Very impressive big integer logic from such an old computer!

On mobile devices click on the cardboard icon to use a VR headset to look around
Look around with directional swipe gestures on touch screens, or use the top-left Google Street View like controls of the YouTube video. Use cardboard or VR headsets if available for more immersive experience.