Sort:  

he usually posts both charts a BTC pair and a USD pair. But, he has said a few times he prefers using USD himself. It doesn't matter I think. From my understanding its the SAME price at the end... USD stays at 1.00
BTC fluctuates all day long. So USUALLY when BTC goes up the price of most coins will go down.... not always but usually.

But i would like to hear @haejin reply again too lol.
Just to understand it a little more

The price action shows the direction or trend but the timeframe is much more difficult to predict. Haejin's has said this many times. The result of that is that the expected price pathway in dollars does not necessarily say anything about the price of bitcoin. E. g. If the dollar price is expected to increase 100% but only 50% against bitcoin, it doesn't mean bitcoin will drop 50% against the dollar. You cannot draw that conclusion because the respective price pathways follow different timeframes.
The other point Haejin repeats is that the dollar trend is a leading indicator of the bitcoin trend.

This question comes up over and over and I think it is because people want to draw conclusions about bitcoin price. Am I missing the point?

Moreover I believe the dollar trade drives the trend and this will become exaggerated as more newbies enter the market thinking in dollar terms.