On a valve with a float spool:
In simple words, that spool has an up, hold, down, and upon farther movement, a detented position,(latch if one prefers)
as it stays where it is put, it does not have a spring loaded return to hold.
It allows both ends of the cylinder's oil, to return to tank, thus called "float"
Edit:
your linked video explains pilot operated check valves and a closed center system, you want an open center system.
and while pilot operated check valves have their place, you do not need them in a simple loader operation.