Based on what I have read in previous threads, Videoscribe can only draw text up to a certain speed. If you set a shorter time than the optimal time, the last few words may just appear without being drawn.
You can try rendering the video to see if the finished video draws better than the preview...
You don't have to animate each individual word. Break the whole script into individual sentences or phrases. Keep everything large and easy to read. use a .1 draw time to make sentences appear quickly with no drawing hand. Even if you use whole sentences and phrases instead of individual words, and only about 10% as many camera movements, you can make the video more interesting to watch with some color and large easy-to-read blurbs.
You might also want to try out Storypix which is free with your videoscribe subscription.
-Mike (videsocribe user)