[David Vaipan]"While I'm familiar with the echo effect in AE, I want the "echo" to be still rather than in motion."
The Echo effect leaves still frames behind moving footage, exactly as seen in the video you linked to. There are options for how those frames are blended together. Minimum (which I'm assuming is the Echo Operator he used) would work well to get this result with starlings since they're very dark.
If you're hoping to achieve the same effect it'd be easiest with a similar setup: locked down camera and the object you want replicated being either the darkest or lightest thing in the shot.