¤ milky moon ¤

I actually had those exact transparency slides in mind when I read this lyric for the first time! I think it makes sense with meaning only 'right here', a photograph is still a depiction of a specific place and exists in the now and in a specific location regardless of when it was taken. Like the suspension of the Golden Gate--
It's very visual to me, but how I imagine it functions in the context of the song is the realisation that over time it can be relieving to 'shed' or 'debride' past experiences by keeping going and looking forward: 'travelling light.' and so, like looking through a stack of old photographs and coming to terms with the past by discarding them one by one you can allay the weight of the past.

My goodness Under a CPell & Jordan~ now I do feel old! Slides were the go to method of keeping photographs for many people, until - well it seems so recent that its hard to believe there's a whole generation who now have forgotten this technology as completely as the slide-rule was dumped from the classroom as soon as electronic calculators emerged!

I've not heard the exact expression (stack of slides) used for this purpose, but the analogy of a set of still photos to demonstrate motion in time is (or was, when I was at school) commonly used to explain the concept. Its certainly what I first thought of when I read the lyric.

Incidentally (but not completely unrelat fly), here's another anecdote from my physics lessons:
To demonstrate how an object picks up speed when sliding downhill, set up an inclined plank, and place a toy car at the top of it. Attach a long, narrow strip of paper to the car, and thread it through a little machine that prints a single dot on the tape every tenth of a second. Start the machine, and let the car go. As it moves off, it pulls the paper through the machine, faster and faster as it accelerates, so that, once it has stopped, you can see a series of dots which show far it travelled every tenth of a second.
The machine is called a ticker. And the paper ... well, you can guess what that's called. Quite why it gets thrown out of skyscrapers when famous people are in town, I can't be sure!

I've always interpreted the New Highland Light Infantry to be an alternate universe version of the 101st Lightborne Elite. She seems to confirms this in the Paste interview.