Im just going to reply here with my solution as well because, in my searching, that other forum/thred did not come up. SO just incase this helps someone using different keywords I will post here as well 🙂
The solution is to save an animation preset with that dropdown selector set to "effects&presets" This will give you an FFX file that you can then use.
The following is my code out of context but should be enough to explain the use case. In my case I am working on an extension and the ffx files will live within the folder structure of the extension.
var ffxFilePath = csInterface.getSystemPath(SystemPath.EXTENSION) + "/ffx/cameraLensBlur.ffx";
var ffxFile = new File(ffxFilePath);
selectedLayer.applyPreset(ffxFile);
Figuring this out has actually expanded how I will be using this in the future for applying multiple effects set with specific parameters with one click from a button in a custom interface.
Hope this helps someone!
- David