Yeah, those honey fungus colonies can be huuuge. I think the first really massive one was discovered in the 90s, but every few years a new one gets discovered that's even bigger.I like that bit where he's talking about the really big ones, several acres? And how it's probably not even the biggest.
There's a great bit in Chanterelle Dreams, Amanita Nightmares about the discovery of the first one, and the news interest it generated. Apparently a Japanese businessman wanted to build some sort of walkway around the forest and charge people for guided tours ("Over here, you can see some fairly generic-looking mushrooms... and over here, you can see some more fairly generic-looking mushrooms... which are genetically identical to the first lot of mushrooms! Promise!"), and a news team from CNN even wanted to take a helicopter over the forest to see the "giant fungus".
Since "fungus" is synonymous with "mushroom" in everyday speech, I do have to wonder if they thought they were going to see a single mushroom literally several miles across. (Although I suppose it's not impossible that you might be able to trace a sort of 'fairy ring' of dead and dying trees, I dunno.)