I have to guess that the Movie Maker would've been this tool that allowed someone to make movies as if you were in Blender, though rather simplified. For example, you have to make a scene for a character walking. To make it walk, you have to take a marker and drag it somewhere. To make the character go in multiple directions while walking, you would press a button (preferably the Alt button on your keyboard) to make a marker between the destination marker and the character, and of course, you can make more markers. Of course, you would likely want to change the character's walk to a run (or vice versa), or make it jump. The actions panel lets this happen.
When you select a movement trail, the actions panel displays two options: run and jump. Of course, the 'crouch' button would be selectable at all times, and 'jump' would be in the normal 'actions' tab. Of course, like in the ingame movie maker, the actions and emotes can be toggled for a certain scene, and for a certain amount of time in a scene.
As for text, you can fairly simply add text to a scene, said text only appearing for a set amount of time, changeable via the 'Movie' menu. But besides adding text, you can upload files from your computer to add new music, and even give the characters voices! Thankfully, if you assign an audio file to a character, the lipsync will attempt (keyword 'attempt') to sync up with the audio.
Now for the part that can either be really fun, or really tedious. Animating your characters. Not dissimilar to Blender, all characters have skeletons (informally rigs) that can be animated. When you have a character selected, the 'Movie' panel will give you the option to go into 'Skeleton Mode'. In Skeleton Mode, the timeline gains a new feature: keyframes. Almost exactly like within Blender, keyframes are your ticket to animating your movie. Thankfully, all characters are IK rigged, meaning you simply have to move a paw up and down for the entire leg to move. This can be the gateway to far more realistic animations than the ingame FeralHeart engine allows! Unfortunately, you are unable to edit the facial features of a character. This is what emotes are for, anyways.
So, is this a good concept for the movie maker, or no?