And if you read up on that place they use fresh stream water from where the fish live in the wild, Most of us don't have stuff like that to use in our tanks in the U.S.
Not likely. That farm is based in Asia, Thailand I believe, not South America where discus are found in the wild. Nor is the water "fresh stream water". (see below)
http://www.youtube.com/watch?v=i4IWBx2gSl0
Lucky Tropical Fish Farm Water Fiberglass Storage Tanks. We have 9 of them, each storing up to 2300 gallon and a total of 20000 gallon to be used each day because we are changing our water 100% twice daily.
And to add to that, I haven't cleaned my filters in "old fish tank water" as you stated should be done, ever. I clean them in clean, dechlorinated tap water.
In this instance the OP clearly stated:
it was dechlorinated and the filters ran for maybe 1 n half hour
.... which getting back to my previous point, which neutrino stated so well;
It depends on quality and consistency of your new water vs. tank water.
I have set up many a new tanks with 100% freshly dechlorinated tap water, and well seasoned filters with not even so much as a tiny hiccup. Many times, over many years - but my tap water always closely matches my tank water.
How hard the water sprayed down on those discus in the video has nothing to do with this discussion, at least not from my perspective on water parameters.