Sometimes I do write it out, if I'm doing a video on a complex subject, though even then I only narrate the quotes or important facts, because it's so difficult not to sound stilted. When I started doing YouTubes a few years ago, I experimented with autocues but the results were terrible! Voice to text is amazing. Try it. It might take a short while for the software to get used to your accent, but you'll be amazed at how quickly it gets to know you. When I travelled to Costa Rica a few years ago, I used to scribble in a jotter using a pencil, while swinging in a hammock. Later on, I would dictate it all into "voice to text". You have to make a few corrections, but not many.