Why would you need to use this setting
First, what you need to know - Apple Search Ads keyword match setting works not like it is expecting to work. Even if you select «exact match» setting for a keyword, Apple Search Ads will drive you impressions for another keywords too, that are similar to the exact keyword.
For example, you have a photo editing app and you have a keyword «photo editor» with exact match. Chances are, that you will have impressions for «video editor» keyword too, which will be absolutely irrelevant for your app, and will spend your budget.
To prevent this situation, use campaign negative keywords feature and all all video related phrases as negative for your campaign. That will save you money for sure.
