Awesome - looks like a really easy and quick way to get started. I'll be trying this out this weekend. And good job on the video - you got right to the point :)
I'll be making more to cover all aspects of the API: 8 or 9 3-min videos. I think that's all it will take for anyone to become proficient with Flask-Ask and the Alexa Skills Kit. They're easy.
If you try it out this weekend, the Ask constructor has changed from the one in the video
Ask(app)
to
Ask(app, "/")
Also, you don't need to add /_ask to the end of the ngrok URL anymore.