AMP Story Challenges for Video

### Description

Hello AMP Team,

I hope this email finds you well!

We are currently working on AMP storytelling for Video/VAST. However, we have encountered some challenges during the implementation of AMP story for video. These challenges include:

1. When our video ad is positioned at the 5th position, users sometimes encounter the ad while visiting the 4th position. As a result, when users reach the 5th position, the ad is already completed. Could you please provide a solution so that the ad is rendered only when users visit the ad section?

2. Due to issues such as fill rate, capping by demand, and others, we sometimes experience empty ad displays. Is there a way to remove the ad feed in such cases?

For reference, we have shared a test page below:
https://textfeed.howgeneric.com/StoryVideoTest.html

Thank you in Advance

### Reproduction Steps

Hello AMP Team,

I hope this email finds you well!

We are currently working on AMP storytelling for Video/VAST. However, we have encountered some challenges during the implementation of AMP story for video. These challenges include:

1. When our video ad is positioned at the 5th position, users sometimes encounter the ad while visiting the 4th position. As a result, when users reach the 5th position, the ad is already completed. Could you please provide a solution so that the ad is rendered only when users visit the ad section?

2. Due to issues such as fill rate, capping by demand, and others, we sometimes experience empty ad displays. Is there a way to remove the ad feed in such cases?

For reference, we have shared a test page below:
https://textfeed.howgeneric.com/StoryVideoTest.html

Thank you in Advance

### Relevant Logs

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### Browser(s) Affected

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### OS(s) Affected

_No response_

### Device(s) Affected

_No response_

### AMP Version Affected

_No response_