If someone clicks a TrueView in-display ad, where do they land?
The ad’s destination URL
The advertiser’s YouTube masthead
The video on the YouTube watch page or advertiser’s channel
The advertiser’s website
Clicking the ad will deliver a user to the YouTube watch or channel page to view the video rather than playing the video within the ad unit itself.
Read more here: https://support.google.com/displayspecs/answer/6227733?hl=en