This video discusses about the mistakes caused by trading during wrong hours. Wrong trading hours means when there is less liquidity faced by markets. Trading during these times of low liquidity affects your trading psychology to lose money.
For example, look at this USD/CAD chart. The London session experiences the most volume when compared to other trading sessions, followed by the US session. The Canadian dollar is correlated with Crude Oil. It is important to pay attention to macroeconomic data release related to oil. This also affects the performance of the Canadian dollar. So, you will experience high volatility during these hours of data release.
Some currencies like ruble, you cannot trade during certain hours. This is due to the broker limiting the trading hours. Currencies like South African Rand and the Malaysian Ringgit experience very liquidity during most of the trading hours. So, you can trade those pairs that have high liquidity during most of the trading hours, like the EUR/USD and the GBP/USD pair. So, avoid using trading hours of low liquidity, and pairs that do not move much in a day.