During the worst financial crisis in decades, Warren Buffett never lost his faith that the U.S. economy would recover.

“The factories don’t disappear, the farmland doesn’t disappear, the skills of the people don’t disappear” during a crisis, he told The Wall Street Journal recently. But “there’s no way of knowing, when you’re in a situation like we were in in the fall of 2008 or 2009, when or precisely how it will end.”

Mr. Buffett, who is chairman and chief executive of Berkshire Hathaway Inc., sat down for a video interview with The Wall Street Journal to reflect on the causes and legacy of the financial crisis that hit its peak a decade ago.

He also recalled his own role in responding to the crisis.

Berkshire is known for having the ability to do deals when other companies are strapped for cash. Mr. Buffett has famously said his strategy is to “be fearful when others are greedy, and be greedy when others are fearful.”

During the crisis, Berkshire helped rescue blue-chip companies that included Goldman Sachs Group Inc. GS -0.08% and General Electric Co. In total, Berkshire’s investments in September and October 2008 exceeded $15 billion.

But Mr. Buffett also turned down requests for financial lifelines from some struggling companies. He explains in the video above why he declined to help Lehman Brothers Holdings Inc. and American International Group Inc. AIG 2.23% during the 2008 crisis.

“One of the lessons of the 2008-09 experience…was the fact that every company in the United States was a domino, and those dominoes were placed right next to each other,” he said. “So when they started toppling, everything was in line.”

A decade after the financial crisis, billionaire investor Warren Buffett explains what was behind the 2008 mayhem, what we can do to limit the damage, and opportunities missed last time.

Write to Nicole Friedman at nicole.friedman@wsj.com