They made a cool thing. It is valuable to me. I paid for it, and we're done.
The app downloads once and doesn't need an internet connection. If you drew a Venn diagram of "Times I want to Know How to Tie a Specific Type of Knot" and "Times When I Am Out of Cellphone Range", there would be significant overlap between the two circles.
I'm not a particularly good follower of technical diagrams, but I find the instructions to be very clear and easy to follow. It's rare that I don't get a knot right the first time.
I've secured tarps, tents, clothes lines, gear onto vehicles and (most recently) a mountain bike that was missing its rear suspension, all thanks to this app.
Here's the link to the app available for various devices: https://www.animatedknots.com/shop
EDIT: I forgot about the fishing knots. No matter how good the app is as a resource, I always get confused and frustrated by fishing knots. But I also get confused and frustrated by fishing, so I can't really blame the app for this.
"Do you love advertising?
We need to apologize in advance, because our apps are nothing but knots. We are sure that there are other apps that will suit your needs."