There seems to be a pattern here - even though I have looked at only 5 examples, there are many more featured on the website. First of all, the square format remains the same throughout - but I suspect it is to stay consistent and is required from the designer by Ten Dollar Fonts.
The majority of the typefaces have a background image to give the style context or to tell a story. It improves the presentation and gives depth to the typeface, and keeps the slides consistent. My favourite example of this is Alpine, where the designer used different images of Paris that related to each other to create a set of promotional material that is visually engaging and promotes interest.
Something else I have noticed is the glyphs are usually kept separate from the letterforms and sometimes the numerals too. It helps to break down the font, and to prevent it from being too overwhelming.
Links to the fonts examined below:
Zona Black Regular
EDIT: Found the designer of Alpine on Behance - Maarten van t' Wout. He included this nice little GIF, which I thought was an interesting way of promoting the font. It shows each letterform on a large, clear scale and is suitable for web as it is a high quality image with a small file size.