A point of clarification: when the narrator says that the optimal temperature of a light bulb is 3200 K, where “most of the energy is emitted as visible waves”, that’s not really true, though what Planck originally calculated may have been for the peak visible emission without significant UV, which is what is implied. The range from 400 nm to 700 nm (i.e. the visible spectrum) represents only about 10% of the emitted energy of a blackbody, and for tungsten-filament bulbs (whose emissivity, or how much it acts like a blackbody) varies with wavelength, the efficiency is lower. You can get a higher efficiency at higher temperatures, but tungsten melts at just under 3700 K, so heating it up more is a problem — it gives off more UV and it melts. There’s also the desire to have the spectrum match the response of the human eye, which is more than simply emitting a lot of light in the visible range.