Like Michael said, things flicker, especially at lower frame rates like 23.98, if the scroll is moving too fast. This applies to text, graphics, and live action elements. With live action, usually an optical motion blur is inherent, but if you have high shutter speed live action, it will do the same thing.
Probably not possible, but increasing the frame rate of the scroll and your timeline to 60 would probably fix it.
Best regards,
Kevin Camin