In the screencast I start off with the USDollar index and look at the Yen.
The US Dollar strength affects 'everything': forex markets, stock markets, and commodities. There are inverse correlations.
Most of the times the DAX doesn't like a strong Euro, Wall Street doesn't like a strong Dollar, and the NIFTY doesn't like a strong rupee. There are reasons for this overall pattern - which understanding of it doesn't really help much. The point is that traders can gauge probabilities based on the strength of various currencies.
The Yen and the US Dollar are safe-haven currencies. This means that in times of stock market corrections and crashes, expect these two to strengthen (in general). The correlations are not perfect.
Overall I'm refining a very different system of following trends using the Vervoort and the Variable Moving Average (both freely available on Tradingview).