Node side source codes of CAI weather forecast app shown in the video (https://youtu.be/tOlYWKifhUI).
If you would like to use this source code for your application, replace the following code by your own APPID provided by https://openweathermap.org/.
[File: server -> routes.js] const appID = "(Replace to your APP ID)"
Currently the URL (https://www.metaweather.com/static/img/weather/) to get the weather icon is unavailable.
This URL is assigned to the variant "weatherIconURL" & "weatherIconPngURL" in this example.
Because I cannot handle the API provided by https://www.metaweather.com, sorry but I cannot help you.
So please find the other weather icon provider, or create the icon (image files) by yourself and use it.
=> Currently there is no problem to access above API and the application works well and get icon images as expected.