In don't know how much the advertising industry creates greenhouse gases but like any other human activity, that's a lot. From employees driving to work to the electricity needed to run the servers.

In this case, I don't think the dumpster fire produces more than a few kW of heat. If it was done inside an office space, it probably wouldn't be powerful enough to heat to room to a comfortable temperature. The server infrastructure required to stream the video most likely produces more CO2 than the fire itself, and I don't usually see an ad on web net saying "we bought carbon offsets to compensate for the greenhouse gases that video produced".

Here there is a visible fire, so people think "OMG, the planet", not realizing that their computer may be connected to a much larger fire in a coal plant.