From Independent Political Report:

The short video above shows 2012 (and possible 2016) Libertarian Presidential candidate (and former Republican Governor of New Mexico) Gary Johnson falling over from a “heart attack” as former Congresswoman Ann Marie Buerkle described the dangers of marijuana, including, she said, increased chances of heart attacks. Johnson and Buerkle were among the panelists discussing the issues of legalization, decriminalization and drug prohibition at CPAC (the Conservative Political Action Conference) near DC.

So far, I have found coverage of Johnson’s participation at CPAC at Syracuse.com, The Hill, ABC News, MSNBC and the Colorado Springs Gazette.