Final answer:
When a placement media cost cap is reached, reports will not reflect impressions and click metrics, Campaign Manager will stop calculating and reporting media cost for the placement, and the placement will be paused until the cap is removed.
Step-by-step explanation:
When using a placement media cost cap, once the cap is reached, the following will happen: Reports will not reflect the impressions and click metrics. This means that the analytics and tracking of impressions and clicks will no longer be available for that placement. Campaign Manager will stop calculating and reporting Media Cost for the Placement moving forward. This means that Campaign Manager will not continue to track and report the media cost for the placement once the cap is reached.
The placement will be paused until the cap is removed. This means that the placement will no longer serve ads until the cap is lifted, ensuring that the media cost does not exceed the specified limit. Ad-serving fees won't be charged. While not mentioned explicitly, it can be inferred that ad-serving fees will not be charged once the cap is reached.