Two reasons, kinda. First, dub packs were intended to be compatible with the gameshow studio, so it's the same format but with additional dub data. Second, and I'm gonna throw the Godot Engine under the bus on this, video seeking isn't a thing in the version I've been developing The Choicer Voicer with. You'd think it should be a normal thing to have, but in Godot 4.4.1, you can only play a video from frame 0
You could also be lazy with it and just use the same image of each character for most lines. I would do that sometimes.