Well... I could see it on heavy equipment such as Rabbit stated for example.
but it IS "Harbor Freight"... not exactly a stellar name...
I may not be an expert here, but I am pretty sure that I could buy a cheap fuel pump, get a few fittings/hoses, & make my own flusher for less than 50.00. Then I would just pour in the new...
Couldn't be too hard....
I hear of people doing this to cool down trans fluid at the strip between rounds...