No, you don't need to pay with attention either. The ad pays out when the ad is displayed. If you stop the playing of the ad, they don't get paid. If you leave

No, you don't need to pay with attention either. The ad pays out when the ad is displayed. If you stop the playing of the ad, they don't get paid. If you leave the TV on and go to the bathroom, or even if you change the channel, the TV station still gets paid. You don't owe the advertiser anything unless they're paying you directly. You owe the content creator (a youtube channel) and the content distributor (youtube). The advertisers are aware of this and it's calculated into their rates. If it's an attentive view, the rates are much, much higher.