Sometimes a voice (picture or video) is worth a thousand words - adds teacher presence  and immediacy.

An important proviso; like any technology, it can be done pointlessly, badly, counter-productively. 

As much as anything, inclusion of podcasts usually implies that the creator cares enough to put effort and personal energy into creating a good learning experience. The caring of the teacher is among the very top factors in motivating learning in an educational/training setting. It is very hard indeed to extricate the enormous benefits of that simple fact alone from anything that is innately valuable about podcasts themselves.

A further benefit is that it almost always increases time on task: time spent listening to a podcast provides more opportunity to think about, reflect on and generally connect knowledge gained in other ways. Again, this is not so much a necessary feature of the technology itself as a useful side-effect of using it.

Animated gifs come to mind. Just because we can do it doesn't mean we should. That said, I know that well-designed podcasts can improve engagement and help students grasp elusive concepts. (I learn a lot from YouTube )

However, I think it is more foolhardy than brave to venture beyond a talking head without some support from a visual designer and/or videographer. The medium is the message, and badly designed (or undesigned) media can convey the message "this is silly," or  "this person is an amateur" even though you may be an expert in an academic field.

So ...

If a monkey snatches my camera and takes my photo, then my photo is in public domain.

If a person snatches my camera and takes my photo with my camera, he owns the rights to my photo.

What if a photo is taken by a robot which is programmed to perform actions at random. If it takes my photo, do I own the rights or is it public. If I own the robot, do I own the rights to pictures it takes? If not, why not? I would be liable for any damage it causes.

Since wildlife is owned by the state, doesn't the state own the rights to this photo.

Which countries recognize the personhood of monkeys?

@Mary - possibly Belgium?

I hate to give ammunition to those who assert property rights over something that occurred by chance and that involved little visible creative effort. However, there might be a case here that this is not public domain, despite apparent consensus that it is.

I have a dog-cam that hangs around the dog's neck and that takes pictures at regular intervals. The vast majority of these are of course rubbish, but I have a great picture that our dog took of me as my profile image for Skype. Neither the dog nor I played any conscious role in taking it, though I guess I did consciously set the camera in motion in the expectation that there might be some interesting results and I did deliberately encourage her to run towards me. However,  by the criteria suggested here, they might be considered to be public domain. The important issue here is that I played a very active role in selecting one that has value from a very large number that didn't. To some extent, albeit here in a more constrained way, this is what any photographer does when taking a picture-  to consciously select an image from a range of possible images. 

The owner of the camera in this case actively chose it from a range of others and, I'm guessing from the relative dimensions, probably trimmed it and maybe even adjusted some aspects of the colour balance and so on. This act of choice is what makes a photo a creative work in the first place. The fact that the choice is more constrained than it would otherwise have been doesn't affect the issue of whether a creative choice was made at all. A similar case might be made for some found or accidental objects that figure in dada art. For instance, the shattering of the glass in Duchamp's nude ascending a staircase or his R.Mutt urinal. On the other hand, if I picked out a particular pot that someone else had made on a shopping trip because of flaws in it that I happened to like, would I be the copyright holder? Probably not.

Interesting stuff. 

Thanks for comments Carmen and Nazim! I've got hold of the book and will explore: sounds like an interesting perspective that parallels some of my thinking albeit in a very different universe of discourse. 

Re laziness, I've not come across unequivocally clear direct evidence yet of the positive side effects of offloading cognition. Intuitively it seems likely that we ought to be able to benefit from the spare brain capacity that is released through doing so and there's no doubt at all that our ability to do so has been by far the most significant and necessary factor in all human progress for millennia. There is also plentiful evidence of positive changes in some brain functions for a wide variety of computer-mediated tasks like gaming and searching, but not correlated with diminution in capacities elsewhere.  I'd be really interested to learn whether there is any direct relationship at all between increased reliance on knowing where to look and increases in our other abilities.

BBC News also covered this story. They included a link to Wegner's chapter wherein he proposed the transactive memory concept.

I don't see the offloading of factoids as necessarily a bad thing. Keeping track of placeholder data is a lot less mental overhead than memorizing the information wholesale. Building out an external mind allows us to focus energy on problem solving, pattern matching, and understanding overall systems.

Ian Stewart and Jack Cohen discuss the related concept of extelligence in Figments of Reality:

All the extelligence in the world is useless if you lack the intelligence to use it; on the other hand, without extelligence we humans would still be back in the caves, rather literally reinventing the wheel in each generation. We are what we are because of a remarkable complicity between intelligence and extelligence. Intelligence invents but cannot reliably and accessibly remember what it has invented; extelligence can remember but (on the whole) not invent. Extelligence deals in information; intelligence in understanding.

I like the idea of extelligence - useful concept

- Interested person

Ideas about natural selection also applying to culture might be relevant to this....

Thank you Jon! I was particularly interested in the graphics. Attempting to visually portray networked activity on the Web is a challenge and these graphics may help me.