"If you think international is never going to work, you should clearly be selling the stock." he said. "They are making a lot more money than they show on paper," choosing to take their DVD cash flow and their streaming cash flow in the U.S. and "plow it into building international."
Two years ago, Netflix stock was in the tank after the company abandoned that Quickster spinoff of its DVD business. Shares are now up more than 350 percent since then, attracting high-profile investors like Carl Icahn and Bill Miller.
In a letter to investors, Netflix CEO Reed Hastings wrote:
"In calendar year 2003 we were the highest performing stock on Nasdaq. We had solid results compounded by momentum-investor-fueled euphoria. Some of the euphoria today feels like 2003."
Said Greenfield: "We've been a huge bull on Netflix. We put a buy on it at $170 back in April. When it broke through $312 just in mid-September, we thought that valuation had gotten a little full. ... That's obviously 80 points ago" based on the stock price Tuesday morning. "There's clearly momentum here, but we thought it was a little too rich to be aggressively buying at these levels."
(Read more: What to expect at Apple's next event)
On Monday's call, Hastings said he was "hopeful" deals with Comcast (the owner of CNBC) and other pay television providers can be reached to offer his company's $7.99-a-month movie and TV streaming service through their set-top boxes.
"Remember most of the set-top boxes across the country … are not easily upgradeable," Greenfield said. "It's going to take long time to roll out, even if [Netflix] could get broad deals done.
—By CNBC's Matthew J. Belvedere. Follow him on Twitter @Matt_SquawkCNBC.