To help you ...
Hidden Valley is a brand name.
Ranch Dressing is a salad dressing .... white, made from buttermilk and some herbs/seasonings.
You usually buy it prepared in a bottle. The package mix that PamESue's recipe calls for would be powdered stuff ... and you would likely add milk (or water?) to it for its normal use to make dressing.
Likewise the McCormick's Au Gus (I think a typo and should be Au Jus)
McC is a brand name ... and this would be a powdered mix to make a seasoned Au Jus for meat.
Now I am guessing ... the two put together in the crock with the butter are adding seasonings to the meat.