Disney's market cap is about $320B, and Netflix at about $280B. It isn't unreasonable to expect that YouTube would be valued at at least that if it were valued independently (Alphabet overall is $1.9T - YouTube as 15% of that value seems reasonable).

YouTube seems to be on track to overtaking Netflix this year in terms of revenue as well, if it hasn't already. [0]

[0] https://www.marketwatch.com/story/with-skyrocketing-sales-yo...