I was in the room when Warren Buffett gave a surprise interview at Berkshire's annual conference. The mood swung from excited to gloomy, then hopeful.

Warren Buffett called out "gambling" and the dangers of deepfakes in a surprise interview.

Carlos Barria / Reuters

• I was in the room when Warren Buffett unexpectedly sat for an interview on Saturday.
• He warned of a "gambling mood" in markets during Berkshire Hathaway's annual meeting.
• The legendary investor also underscored the threat posed by nuclear weapons and deepfakes.

I was in the room when Warren Buffett sounded the alarm on "gambling" in markets, nuclear weapons, and deepfakes on Saturday.