It's possible,even usefull, to be able to swap out the geometry on the timeline. The best example is if you want to have a character to change as a result of say, a blast from a strange transformation wand (ala hpotter style). Or, perhaps like in my example, you may want the characters to cycle through during a handshake. The key is to load a new geometry in the properties tab (select object, right click properties, then select the geometry of a prior loaded character.) Most will allow a swap out, but not all. Also you may find some weird eyeball repositioning.
This also works on props, so next time you want a burger to turn into a lemon, just do it in the timeline!
BTW to get the camera to do the move in the sample clip, get a sphere to travel along a path strung between the characters, then have your freecam follow a curved path that sweeps around the talent. Now if you get the freecamera to target the sphere at the start of the timeline, you'll have some great control over when the camera moves and also when it pans!