3:10 - "The modeler may want to merge the parallel flow back into the normal flow" using a parallel gateway. In my opinion, you cannot do that, because the non-interrupting event may not appear at all, thus "Do parallel activity" will not execute. When the "Do activity 1" finishes, the process will stuck on the parallel gateway, having only one token from the left, and never having the other one from the bottom.
3:10 - "The modeler may want to merge the parallel flow back into the normal flow" using a parallel gateway. In my opinion, you cannot do that, because the non-interrupting event may not appear at all, thus "Do parallel activity" will not execute. When the "Do activity 1" finishes, the process will stuck on the parallel gateway, having only one token from the left, and never having the other one from the bottom.