For one, competition from Amazon (NASDAQ: AMZN) and Apple (NASDAQ: AAPL).
"I think Amazon and Apple, the reason they're so scary, is that they're not trying to make money off of the subscriptions," McNamee said. "They have a different business strategy."
McNamee said that he doesn't think it's a "winner-take-all" market. But as much as Netflix has dismissed Amazon's strategies , consumers will have more choices than ever, which makes for brutal competition, McNamee said.
"I think there will definitely be too many channels, and I think the proliferation of distribution points is a gigantic threat to the valuations in the sector. But I do not think it's a threat to consumption…I just think as an equity investor, you want to pick your stocks," McNamee said.
"The good news though, is that content wins, and there is more of that coming, and frankly, Netflix is driving that," McNamee said, adding: "This management team has understood the streaming market better than anyone else on earth...this is a company that really has delivered."
Despite an initial slump immediately following the earnings release, Netflix shares hit a price of over $149 a share after hours, above the all-time intraday high of $148.29 set during the regular session at the end of March.
"I personally would not be a buyer here at the highs, because that's not the way I roll, but if you're going to buy something in this space, this is the one you're going to want to buy," McNamee said.
More From CNBC