Half_Life scripted sequence: how was this done?

A Half-Life mod I recently played had a sequence that I can’t figure out how they did it. If anyone can help I’d appreciate it.

At the end of the mod, once you go through a door the viewpoint suddenly shifts and your controls are frozen. You see your Freeman character off in the distance. The viewpoint does an aerial “flyover” of the scene, stops at a certain place, and then your controls are released. You can move your Freeman character, the view automatically faces towards him, but you can’t move your viewpoint.

The thing is, this is not the same as what happens when you issue the chase_active or cam_command options from the console. In both of those, the view is always relative to Freeman. In this sequence the view is always from a fixed point on the map. You can move Freeman all around the map, closer or farther from “ground zero” and the camera will track him but his position is no longer the reference point for the camera. How can I duplicate this “Arena mode”?