Notes only appear in the notes view.
When viewing a slide show using nbviewer.ipython.org you need to click on the slide show icon at the upper right.
Notes about starting a slide show.
Once the slide show has started you will see navigation arrows appear at the bottom left.
The color of the arrows have meaning.
Note the zero (0) to the lower right. That is the current slide number. Subslide numbers are displayed as the top slide number then a dash then the number of slides down from the top, i.e. "1-1" would be the second slide to the right and one slide down.
(More on navigation below - click on the down arrow.)
You can also navigate using a keyboard with the arrow keys or just by pressing the space bar.
The space bar navigates by advancing the same as pressing the down arrow until there are no more slides below, then pressing the right arrow. This way you are guaranteed not to miss a slide.
Next we talk about using notes.
To use speaker notes you just need to do three things.
At this point a popup will appear containing the current slide, the notes for the current slide just below it, and the next slide (either below or to the right, in that order) to the right of the current slide. There will also be a timer showing the elapsed time since the start of the notes view and the current time. If the arrangement is the current slide is above the next slide and then the notes below just zoom out (Ctrl -) until they apear in the correct arrangement.
Press "s" now and see for yourself.
There are notes about notes. Note text will be reformatted to fit in the space provided.
This is what you should see after pressing "s" in the slide above.
This is just show that the subslide is the next slide shown.
This is a quick and easy to use a slide show without having to install any software as long as you have an internet connection.