From the video, it is $2500 for a 25,000 word book, written in 25 days. That is $100 per day writing 1000 words per day. If this takes you 8 hours per day, that is $12.50 per hour. If you can do this every month, that is $30,000 per year. A comfortable wage for some people, and poverty wages for others. It also seems like a difficult pace to research a topic and write 1000 words per day, and seems like miserable work.