Entirely true but if you look at the fluid you can tell in the vids, it's wasted. Smelling it also helps but can't do that on a vid for obvious reasons. Dark by itself doesn't mean bad but the stuff in the video was sludgy and brown/black, not just darker'.Not sure if I would go as far as to say the fluid is bad in a short amount of time. But the facts are:
Mercon LV turns dark sooner than some other ATF’s. Doesn’t mean it’s completely toast,it’s just the nature of it. Truth is, your engine oil turns dark soon after an oil change. Doesn’t mean it’s bad.
The frequency of trans flushes really depends on how you have used the transmission and how long you want to keep it.
If you go to the track or tow often, then change it often.