@nhatminh12369 - unfortunately that sample code is deprecated (we will mark as deprecated soon, since there are a lot of users reporting the same issue) because the youtube html page retrieved by our engine misses the html element containing the number of views.
You can check that yourself running this command
`curl https://www.youtube.com/watch?v=9bZkp7q19f0` -o youtube.html
and check the content of the
We suggest you to run the test above before running the query in order to be 100% sure that the html element you're looking for exists inside the page.
unfortunately that sample code is deprecated
btw, thanks for letting me know, I didn't notice that an html element was missing
ethereum-bridgefor that: https://github.com/provable-things/ethereum-bridge
ethereum-bridgeif you want to on bsc: https://github.com/provable-things/ethereum-bridge