I didn't see any posts about copying from the SD card other than the one I mentioned. You might be able to do it using the URL commands discussed in the thread on that topic, but I haven't tried that.
You are correct: I have written to the SD card only using event-based recording. You might be able to do what you want using third party software (or D-ViewCam); I haven't tried it.
If you were recording to a network drive and not your SD card, it is possible to view a series of snapshots and make it look like a video. Just open the first jpg in Picasa or other picture viewer, give it time for all the thumbnails to load, highlight the first thumbnail and scroll to the right. Depending on how fast you scroll, you can almost make it look like a movie. Not sure how I would do this on the SD card, however.