How to get Alarm Preview (Smart Client) to freeze video at time of alarm

I specify the StartTime and EndTime of the AnalyticsEvent that I send. The Alarm Preview in Smart Client plays the video beyond the EndTime. How do I either get Smart client to display only a still image or play the video only within StartTime and EndTime?

The alarm preview does not support this feature. You can, however, include a snapshot with the event yourself (if you have one) and it will be automatically displayed next to the video in the alarm preview.