As I've pointed out here previously, his claim that he doesn't have to do any fundraising is, not surprisingly, false, and the always outspoken Cuban goes into more specifics. He's been fairly public about all this lately, and I liked his answer about Trump's email question to him why. The simple answer he gives to host Chris Hayes is that conditions have changed. That's the polite way of saying, "He's the Republican Party nominee for president of the United States now. So, such things matter."
Also interesting in the video, though it's only referenced briefly at the beginning, is that a Trump rally is about to begin at the same time, which MSNBC is clearly planning to show some of, and there are a lot of empty seats. It's possible that later in the program, after the interview with Cuban has ended, Hayes might have talked about this more at length, as he focuses on the rally.