On my work computer (PC with Windows 8) I was fully able to use the key triggers and mouse control. On my mac at home (OS 10.10 Yosemite) it does not respond to keyboard shortcuts or mouse clicks on the Windingo character as described in the tutorial. On the bunny dude character in scene 1 it does function.
When keyboard input is being ignored on the Stage, it's usually because the Stage panel isn't focused (blue ring around it showing the last clicked-in panel).
But if the mouse isn't working, perhaps your character isn't selected in the timeline, or the Mouse Tracker behavior is no longer armed for recording (red dot in front of "Mouse Tracker" in the Properties panel when the puppet is selected in the timeline).