I love any type of multitool. I have the one pictured in the image. The axe head isn't very effective, the pick is worthless, but the saw, knife(not pictured here) and shovel work fine. I wouldn't buy another, though there are better one's out similar to this with more features I might check out.
The only issue with putting your shovel head on your walking stick is that processing wood like you were in the video would be awkward, as would using it like a machete going through the bush. Of course, you could just make a make-shift handle as needed too.
That looks pretty sweet! I saw some staves/spears that had a similar modular system, but I always assumed they'd be fragile.
They can be. I find that a cheap concept model usually comes first(what I bought, lol), then others jump on a good idea by adding utility and many times upping the quality as well. It's pretty much, "you get what you pay for."