An increasing number of offers for YouTube credentials has been noted recently on hacker and cybercrime forums, where access to accounts is sold in bulk. Sellers advertise large lists of credentials that are verified for the availability of a YouTube channel and subscriber count. Data comes mostly from infected computers, phishing campaigns, or logs of logins to specific services and then auctioned on forums. Researchers at IntSights external threat intelligence company found that there s an increased demand in YouTube credentials on underground markets.
Source: https://www.bleepingcomputer.com/news/security/youtube-channel-credentials-in-high-demand-on-hacker-forums/