YouTube is forever trying to make it difficult for us to scrape data from their site. They have recently made some changes that made it so that Scrapebox was unable to directly scrape YouTube channels.
Fortunately, there is an easy workaround for this. Simply use the standard Scrapebox harvester and use the following search string: <code>”https://www.youtube.com/channel/*” keyword</code>
Use the keyword scraper if you need to get more results, but do keep in mind that you will dilute how specific the niche is that you are targeting.