Monbiot in the above vid said it's bs, that the FAO have now taken this effect into account and come up with an even higher percentage of ghg emissions from livestock, and that Fairlie is retailing propaganda from Big Meat and is basically a climate denier as a result (from 57:35) Haven't seen what he's basing that on, so can't comment but it seems odd that the estimate would increase if they had really taken those factors into account. Also it fits Monbiot's style of throwing out accusations and guilt by association when his argument is weak, so take that with a pinch of salt... I think Fairlie is right to rubbish the claim that the warming effect of livestock methane is greater than the entire transport sector, given the cumulative nature of the CO2 emissions from the latter.
Hope that clears things up??