This is a cool idea. I suppose it would need some rudimentary analytics over time to work as an actual training tool? One suggestion: For me, at least, my read

This is a cool idea. I suppose it would need some rudimentary analytics over time to work as an actual training tool? One suggestion: For me, at least, my reading relies on the shape of the sentence. And I think for everyone they would be looking at the right edge of the sentence as more words are coming in. So it's really jarring to have the right edge jumping around, and it might make more sense to right-align the marquee.