I followed the video but when I clicked Authorize button, then logged into my Google account, I got this message:
This app isn’t verified
This app hasn’t been verified by Google yet. Only proceed if you know and trust the developer.
If you’re the developer, submit a verification request to remove this screen. Learn more
I am using a Google captcha on my site.
that is new thing in Google. Now everybody works to “prevent” unwanted access to private data, because privacy is hot topic atm :). Just click proceed and you will get token required to access your calendar.
The only option from there is Learn more
That as no proceed option