What is that quote? Arthur C. Clarke was it? Something about how any technology has the ability to be perceived as magic by the primitive mind? That. You can look at historical accounts of Europeans who were making first contact with a race of people in North America, people who had lived in the natural environment for their entire lives and had all the learned skills and instincts that come with that. I'm sure them seeing an Indian "manifest" a fish by snatching it from a stream with their bare hands evoked the same awe that some BF observers have related. Doesn't make it magic, or portal use, or shape-shifting, or whatever the theory du jour is. Just means that they are really, really dialed in to their environments and have crazy skills and perception that appears to be supernatural.
The sound heard by Tom Messick's hunting partner has always intrigued me, as it has many others. It may be explained as a pressure wave generated by infra-sound, being perceived as something close to a door or trap closing. The mind, when confronted with unknown stimuli will also try to catalogue it under the heading of something known. Without confirmation that the original impression was wrong, it is always going to be described that way by the listener.