An advertiser can use a remarketing tag to target people who’ve:
searched on YouTube for videos about products like hers
set up multiple YouTube accounts
posted videos on YouTube that mention her products
subscribed to or unsubscribed from her YouTube channel
Explanation:
To show ads to people who have visited your desktop or mobile website, add the remarketing tag to your website. The tag is a short snippet of code that adds your website visitors to remarketing lists; you can then target these lists with your ads. In YouTube Remarketing lists are created by first linking your YouTube account to your AdWords account. Once you link accounts, you can create remarketing lists that reach people who have done the following YouTube-related actions: Viewed any video from a channel, Visited a channel page, Viewed any video (as an ad) from a channel, Liked any video from a channel, Commented on any video from a channel, Shared any video from a channel, Subscribed to a channel, Viewed certain video(s), Viewed certain video(s) as ad(s)
Remarketing lists are created by first linking your YouTube account to your AdWords account. Once you link accounts, you can create remarketing lists that reach people who have done the following YouTube-related actions:
- Viewed any video from a channel
- Viewed any video (as an ad) from a channel
- Liked any video from a channel
- Commented on any video from a channel
- Subscribed to a channel
- Added any video from a channel to a playlist
Read more here: https://support.google.com/partners/answer/2545661