Democracy Now! web page has a link to the “three-hour” presidential debate, which includes Jill Stein and Rocky Anderson. The reason it is twice as long as the Commission on Presidential Debates is that the format paused the CPD debate and gave equal time to the two minor party presidential candidates who attended the Democracy Now! event in a church in Denver.
The introduction says that Gary Johnson had been invited to the event, but that he chose not to participate. Instead, he issued live commentary about the debate via Google Plus Hangout and Twitter. IndependentPoliticalReport has this link to the Johnson responses.
One of the disadvantages of both approaches is that, probably, everyone interested in the presidential election prefers to watch the CPD debate live, because it is very newsworthy. Democracy Now! would probably get more viewers if it simply deleted the Obama and Romney portions, and let viewers watch the Anderson and Stein responses, so that the viewer interested in their responses isn’t forced to sit through the Obama-Romney portions all over again.