Now I'm looking at this one, attaches to an SSQA plate:
I have one of those that I made out of an old 3-pt log splitter. All in I think I spent about $700 (plus my time) vs the new one's averaging about $3500. Its great. I do the same as in the video only I split it directly into the trailer I haul it back with. Now that I have a tractor also (sort of) I'll probably weld the link pins back on to the skid plate so I can flip it over and use it on the tractor 3-pt and aux if I just ever needed to.
Some things to consider about using an SSQA on a tractor FEL.
Maneuverability - A SS is a zero-turn hydrostatic machine. Tractors typically arent. You're going to spend a lot of time backing up and going forward while turning, instead of just pivoting like a SS will do. Thats going to add quite a bit of time.
Visibility - In a SS I'm right there at the action and can see the log and the splitter really well. A tractor FEL mounted SSQA log splitter the operator will be 20 feet distance from the work looking over the hood and FEL.
Cycle time - In low-flow, a SS is pushing nearly 3 times the flow rate of your tractor FEL (if 6 gpm is correct for your tractor). That's going to take a long while to cycle.
Not trying to dissuade you, just sharing some experience from using those.