Note your Video slide works great. I assume if I have a non You tube video, I would have to upload it to You tube and then place the You Tube URL of the Video in your Video Slide data area.
I will be using Text Slides to describe each slide that follows.
The Text slide is always formatted to center, i.e. if last line has one word it's placed in center of Slide.
It would help to have text color and height selectable to make a slide more presentable.
Also if the text slide does not fill the Text container area. there is no way to vertically center the overall Slide text.