So, I can't be the only one curious about this little tale.
Seeing as how this "intermission" was shown at the movie release, it would prolly be impossible for the viewers to read and grasp the whole tale in a mere 5 seconds, which leads me to believe it's something worth looking at. It's actually simple to understand what's going on if you've read a couple chapters ahead of episode 25, where Hanji explains that Eren's titan form may be able to plug up the "hole" during the breach, if he discovers how to harden his skin similar to Annie's Titan form or the Armored Titan.
However I still think there's more to it then that, it's such a strange thing to put during this episode, hell, it've been strange to put it on any episode considering it's something completley new to both the manga and anime.
So if anyone's got any ideas or clues about what this might indicate feel free to do so :)
In the meantime i'll share a little theory of sorts.
This tale takes place in the year 784, current year is 850 if im not mistaken, the new spin off manga "before the fall" tells of a breach inside the walls 70 years prior to "that fated day." I may just be pulling at straws here but this man's hole could possiblely be the reason for the titan in "before the fall" to just walk in all nonchalantly even though Wall Maria hadn't fallen. Or the "random" dissaperance of the digger could be explained by him becoming said titan.
But like i said, Pulling at straws. :P