"The app I used worked nothing like the slick demo in the video."

This point is very important and I hope to not do the same misstake.

Because I also watched the video, saw what was happening there, looked nice - but trying it for myself absolutely did not work as expected.

In other words, if there is a simple video with features shown - then trying it out needs to be as simple as the video, or it causes lots of frustration.

First time users do not want to deal with setup configs etc. first. This is something you want later.