no its not lower than text, its higher ROI than text for understanding the physics of the world, which is exactly what videos are better at than text when it comes to training data
Does that transfer, though? I'm not sure we can expect its ability to approximate physics in video form would transfer to any other mode (text, code, problem solving etc)
After that, make the robots explore and interact with the world by themselves, to fetch even more data.
In all seriousness, adding image and interaction data will probably be enormously useful, even for generating text.