The 'jacks' in the basement are lolly columns. Those are added because the house settled unevenly and they are to keep the structure from settling more. I have them in my basement. It's not a major issue if they are the correct type and placed properly. I bet the garage is original and the rooms were added later over a deck, hence the sliding door.
Love to watch these! One question - at 1:43 there is a good view of two pipes coming out of the back of the house. The white PVC likely is connected to a basement sump pump, especially because the pipe feeds into that little "pond/pool" area you mentioned. However, what is the rusted metal pipe? My first thought was that it was to connect an exhaust hose to when working on a car in the garage. From the picture, though, it appears the pipe was once connected to the adjacent cement block stack? Anyone have any ideas?
It could be an exit for an exhaust fan for the garage like you said. I have seen similar setups where they may have had a wood pellet stove present as well.
Our website with inventory information is included in the description of all videos. If the property is currently listed, info will be available there.