When should an advertiser, who’s using Campaign Manager 360 to run an in-stream video ad campaign, consider activating default ads for placement?

When should an advertiser, who’s using Campaign Manager 360 to run an in-stream video ad campaign, consider activating default ads for placement?

 

• When serving ads to only desktop users
• When serving ads to any user or device
• When serving ads to only mobile users
• When serving ads to only tablet users