No need to export and re-import. Just put it over your other stuff in the same Project timeline, set the Blend Mode to screen or similar. Works great, saves time.
I've found that on my cranky old Mac rendering out helped to speed up editing and compositing of these types of layers. Definitely would keep things in FCP if the Mac was powerful enough to render and edit with. Interested in your thoughts on this Ben.
Your solution of exporting to a video file and importing that file, is one I've taken to using as much as I can in situations like this... I've found that problems many times... While Plugins are great, in the moment, over time they are a serious problem, simply because they become obsolete, or broken... You've edited your video in one version of the plugin, you need to make changes... except in between then and now, the plugin company is defunct, updates aren't available, or your OS has advanced, and the plugin you used then, doesn't work anymore... You open the project and you get the missing media red screen, sometimes all over the place... Because of this, I have had to do a lot of work in the past that I shouldn't have had to do... I also don't use external plugins much for the same reason... If you need snow or rain, or some overlay like that, then stock footage works best..
