YouTube videos, forum posts, Instructables and a lot of web pages are snapshots of the iOT world at a particular time. Some of these snapshots like videos are impossible to update but YouTube and Google do try to help by ranking new content higher than old content. Their algorithms also give weight to popularity and older posts will be more popular because they have been around longer but don’t assume what you are reading or seeing is still accurate, especially in iOT.
When you search this site always ask for the most recent posts on the subject you are interested in. By default the search results from a Discourse site are ranked in order of “relevance”. That’s a reasonable default for some Discourse sites but not ones like Blynk.
However in addition to “stale” YouTube videos Blynk also provides dynamic assistance through public channels like GitHub. You will have made good use of this dynamic data when you picked up the libraries and the server. If you read through the appropriately named README.md for the server at https://github.com/blynkkk/blynk-server you will see up to the minute information including port 9443 for access to the admin console.