Ads appear every 15–20 minutes. No different from old-school TV, but you can’t skip them unless you pay for YouTube Premium (which then makes them ad-free).
Stream and Chill: How to Find the Best Free Movies on YouTube movies youtube for free
Even if you stick to “free with ads” movies, YouTube isn’t a pure public service. Here’s what’s really happening behind the play button. Ads appear every 15–20 minutes