Climate models? What climate models? We don't need no steenkin' climate models!
Interestingly, water vapor, the variable the video goes into some detail about, is only one of several such variables that have a direct and statistically important impact on climate modelling, all of which the modelers have to basically guess at when running their model, if they're accounted for at all. What's more is that each of these variables (e.g. solar activity, oceanic algae growth, how many trees there are, volume of fresh water run off into the ocean, oceanic currents, overall variation in oceanic salinity, surface polar ice, cloud coverage (particularly in the polar regions), etc, etc, etc) effect many, if not all, of the other variables. An increase in one causes a decrease on another which in turn either increases or decreases yet another and so on. In short, it is WILDLY COMPLEX! It is, in fact, far and away too complex for anyone to have any idea at all about what the climate is going to be doing even ten years from now, never mind fifty or a hundred or a thousand years from now, which is why all the predictions that these climate models have made over the decades have all been universally wrong.
In fact, Earth's ecology is so wildly complex that it isn't even accurate to say that we have any real evidence that the climate is changing in any way whatsoever! The portions of the ecosystem that are both meaningfully measurable and that have been measured are so minute in comparison to the complex systems that make up the "climate" that it would be like trying to predict what IBM's stock price will be two years from now based on how many cars are parked in the parking lot at its corporate head quarters and modern trends in oil prices. (Yes, both the number of employees the company has and the price of oil have an impact on IBM's business.)
Clete