Why does browsersync throw a Cannot GET error?

Question

Browsers

Good evening.
I'll describe the problem right away. I decided to create an assembly on GULP4. I registered all the commands that were needed (npm install --global gulp-cli, npm init, npm install gulp --save-dev, npm i browser-sync --save-dev).
Created gulpfile.js. I registered scripts in it (I attach screenshots)



Also, screenshots of folders:


I have been suffering with this gallop for 2 days already. For the first time, when I set it up and did it for a week. This is how unintelligent I am. I set up GULP according to this video, and before that I set it up - everything was fine ( https://www.youtube.com/watch?v=stFOy0Noahg&t=1115s ).

Can you help me and write what exactly is the problem and why does browser-sync give an error? If you need any more information, then write - I will provide