"We found it was undervalued. We put in a price. Eventually, Disney offered more and we walked away," Roberts, whose company owns NBCUniversal, which owns CNBC and CNBC.com, recounted to "Mad Money" host Jim Cramer in an interview.
But "one of [his] disappointments this year" was that "people then took that and made a narrative that said we didn't love our core business when, in fact, our core business is having a renaissance," Roberts said on Thursday.
Describing a Comcast that has "pivoted" from being a traditional cable and entertainment provider to a technology-focused monolith, Roberts — whose company is still in the throes of bidding on European cable giant Sky — said his focus has turned to innovation, content and connectivity.
And while Comcast's second-quarter results were mixed, with many more than expected high-speed internet customers but slumping video streaming numbers, Roberts said they were essentially symptoms of the changing times.
For one, while Comcast realized that Xfinity customers didn't necessarily want the cable-and-internet provider's full video package, sales of broadband — high-speed internet transmission — boomed.
"In the second quarter, we had the best broadband sales in 10 years and it's a 20-year-old product," the CEO said. "Is that a one-month phenomenon [or a] one-quarter phenomenon? I don't think so."
"We now have 20 tablets and devices in a home," he continued, adding that 10 percent of Comcast customers are "power users," meaning that they use three times more bandwith than the average customer. "What does that mean? It means in a couple years, we all want to be what the power user's doing today, so our capacity is great."
"Historically, whether it was QVC, NBC or AT&T, each acquisition, we have to prove it. We have a show-me attitude by the investors. I respect that," he told Cramer. "My dad took Comcast public in 1972. If you bought 1,000 shares — $7,000 — you'd have just about $12 million. [That's] 17 percent compounded return for 48 years. If you put it in the S&P 500, you'd have about $750,000, about 15 times less money. So we're looking for value opportunities."
Calling NBC "probably the best acquisition we ever made," Roberts also touted his management team's foresight.
"We saw content being more valuable over time. And now, of course, everyone wants to get into content and they're looking for what we bought eight years ago, nine years ago. So same thing, we think, can be true in international, it can be true in connectivity, in broadband. Our job is to be one step ahead and then eventually come to the investors and try to make the case once we've got the goods to prove it."