If we’re getting someone to speak to camera, it’s always best if they can do it off the top of their head – it seems more natural and comes over better. However, this might mean breaking the piece up into several parts in order for the speaker to think about each one satisfactorily in advance, and that means a more complex editing job at the end.
The alternative (unless we want the speaker to be referring to notes off-screen) is a teleprompter. There are good low-cost kits for setting these up to work with existing cameras, such as the Parrot Teleprompter, but if you’re happy to record the video with an iPad, a teleprompter can be set up with just a low-cost app. Video Teleprompter looks like it’s the app to go for here.
You might be surprised at the features available on app-based teleprompters, including voice-controlled auto-scrolling and more. There’s a good video review of the options here.