Look at his actual arguments and data. He cites sources thoroughly IIRC.
I don't think anyone would argue against the idea that fossil fuels have helped technological progress over the last century and a half, which seems like the core of his thrust.
The problem is the almost dismissive attitude about the future prediction consensus. Generally, the scientific consensus is against his statement: "The [future] warming impact of CO2 is mild and quite possibly positive".
From there, it seems like he is selectively framing his arguments. For instance, higher CO2 concentrations does increase crop yields (as stated), but scientists believe this will be offset by higher temperatures and drier conditions. (https://www.nasa.gov/feature/goddard/2016/nasa-study-rising-...). Statements like "Warming is almost universally desired among civilizations" seem to ignore that there is such a thing as too hot for the human body, let alone for other things such as food or having a reliable water supply (http://www.fao.org/3/a-i5188e.pdf).
It seems like a strange bias to think that there is zero room to improve our energy pattern and sources compared to what we have now. Or that only three industries (hydro, fossil fuel, nuclear) will possibly ever exist to provide cheap, plentiful energy. (For a start, I'll ding him an additional point for forgetting about the original cheap, plentiful energy source humans used: "traditional biomass". EG: wood, crop waste, dung, etc.)
But many implicitly ignore the benefits of fossil fuels. I hear many variations of the comment I originally replied to, i.e., "even if there's no climate change, reducing fossil fuel use is pure win". I think many imagine we could keep roughly the same quality of life with the majority of our power coming from solar panels and wind farms. Smarter environmentalists realise this is not true, but the general public is very confused on the issue, especially as the more rational greens get lumped in with the activist crazies.
(One very important point in to explain Alex's context: many greens (not all, granted) are opposed on moral grounds to nuclear, and even to hydro, which floods valleys and messes with nature. The root of this is the desire to minimise human impact, but "minimising human impact" is ultimately at odds with "maximising human flourishing").
to think that there is zero room to improve our energy pattern and sources compared to what we have now
He doesn't think this. Obviously improved nuclear power, ultimately fusion power, is the real long-term solution. However, hopes that we can significantly improve solar or wind power are doomed to crash into reality -- there's fundamental limits to how much energy you can extract from the wind (https://en.wikipedia.org/wiki/Betz%27s_law) or from photons (https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limi...). Burning wood and dung works for poor countries that lack infrastructure, but it's more expensive that fossil fuels, and more polluting, even more polluting than coal.
Yes, there are limits to extraction, but solar and wind power's advantage is that, location wise, it is viable in far more places than something like hyrdo power; it also can be set up in a more decentralized fashion which can be advantageous for some scenarios (remote areas with little existing infrastructure for instance). I've always thought that solar and wind's biggest challenge to overcome is more the non-continuous nature of that power source. At any rate at this time I don't think it's safe to predict what a long term solution might be or might not be. There probably is (as like now) no single solution that is right for every location.