When setting up targeting groups for video ads, it’s most effective to:

A) select a maximum of 3 targeting groups
B) select at least 5 advanced audience options
C) target broadly by demographic groups, topics, or interests
D) target narrowly by demographic groups, topics, or interests

The correct answer is:

D) target narrowly by demographic groups, topics, or interests

Explanation: These targeting methods are added at the ad group level. It’s important to know that with each targeting method you add you narrow, not widen, your targeting.
Read more here: https://support.google.com/partners/answer/2454017