Vacuum Excavator for crawl space
I read the article you linked to.  Looks like it would work if you have the right soil conditions, a lot of time, a lot of help and the patience of Jobe. One concern I would have is if you ran into large rocks or wet soils.  We have excavated several buildings over the years using the railroad ties and jacking method followed by a mini excavator. Here in the glacial soils of the northeast, we often run into large boulders that would be impossible to remove without heavy equipment.  The other caution would be to pour concrete or an other stable footings for the new post supports. This would be tricky if they are done one at a time as you excavate deeper under the building, especially if building has already settled and is not level at the start.  Some level reference would have to be maintained throughout the process. This is not as easy as it may sound, and would require some jacking, sistering of floor joists, or a new set of carrier beams etc. along the way. This vacuum method may be OK for small buildings, but could be troublesome or dangerous for larger buildings or for inexperienced builders.  Be careful.