You can probably modify this code to do what you need to. To change the
filesrc (I think):
- Stop the pipeline (put it in GST_STATE_READY)
- Change the location property for the filesrc
- Start playing again
To find what time the user clicked stop, you can probably either create a
GstClock or use the pipeline's.
There will probably be a slight delay when loading the new file, so you
might want to pre-load the file in a different filesrc element and use
input-selector to change which video is showing.