No, the mold on meat isn't especially bad. It won't eat your insides. But still, moldy meat is worse than moldy plants.
Mold itself isn't a strong health concern. It can't cause an illness, and doesn't grow in the human stomach. There are some kinds which produce metabolic byproducts poisonous for humans, and this means that you shouldn't eat moldy food, because you don't know which type of mold it has, unless you know that the type is benign, such as in a piece of Roquefort cheese. But if you see a moldy vegetable and throw away the moldy part plus a generous part of the healthy-looking tissue (mold "roots" are invisible without a microscope, what you see on the surface is only its "flowers"), you have a non-neglible risk of ingesting a small amount of mold, but the probability of it containing toxins strong enough to cause symptoms is very, very small. So it is reasonably safe to eat the healthy parts of plants which had mold growing somewhere on them.
The problem is that mold grows in the same conditions as bacteria do, only more slowly. When food is stored under improper conditions (or for too long a time under proper conditions), if a mold starts growing and reaches a stage where it is visible, in this time all the bacteria capable of growing on this food will have multiplied into unimaginable numbers (remember, bacteria grow exponentially, with a generation cyclus often as short as 20 to 30 minutes).
Both plants and meat in our food supply have some chance of contamination with pathogenic organisms like salmonella, E. coli, and something-resistant SA (it isn't only MRSA which is bad for you, a staphylococcus can be resistant to any number of antibiotics besides methicillin). But these grow on protein, not on vegetables (insofar, your logic for the mold holds). So you are reasonably safe eating a thoroughly washed vegetable - even if it does have some human pathogens, there will be only a handful of them, even after days of non-refrigerated storage, and almost everyone's immune system can cope with that. But if you eat meat which was left in microorganism-friendly conditions for long enough that mold creates visible spots, you are eating colonies of bacteria numbering in the billions, even after cutting the moldy part away. If one of these colonies happens to be a pathogen, your risk of getting ill is very high.
Actually, it was probably high enough hours or days before the mold became visible. Heating to the guidelines temperature doesn't ensure that all bacteria die, it ensures that out of a hypothetical contamination, only one in 1 000 000 is left alive. But if left in a pot full of food, these bacteria left can start multiplying and reach their previous numbers after a few generations. So be mindful of the time cooked food spends in the fridge, even if you don't see or smell any alteration. But if you see mold on meat, it means that every reasonable risk limit for eating it has long been crossed. Just throw it away, period.
If you use yogurt (or cultured buttermilk) it sounds like the creator of the recipe is trying to get the Lactobacillus in the yogurt to start metabolizing some of the components of the mixture. Otherwise, it sounds like they want some random yeast to start the fermentation for the bread. There is definitely a risk of other potentially pathogenic organisms growing also as there is a source of moisture and food with those ingredients and a suitable temperature.
For buttermilk or yogurt specifically:
From a safety standpoint, you would need to consider what the load of pathogenic bacteria is compared to the intentionally inoculated Lactobacillus as the Lactobacillus may interfere with the germination of B. cereus due to creation of an acidic pH.
In general:
As per http://smas.chemeng.ntua.gr/miram/files/publ_77_13_1_2004.pdf it takes approximately 20 hours for a 2-log increase in concentration of B. cereus (1 bacteria dividing into 100 offspring), and as per http://www.cdc.gov/mmwr/pdf/wk/mm4310.pdf it takes 10^5 B. cereus per gram of food for symptomatic illness, so your initial concentration in the ingredients (assuming the growth conditions in the first paper) would need to be 10^3 per gram overall of viable organisms to get to the toxic level in this time frame (potentially meaning that your ingredients carrying B. cereus in and of themselves would need to be relatively close to the toxic range to start since not everything would be presumed to be contaminated). Since it takes time for spores to germinate, if we are talking about no viable organisms and spores only it would take an awful lot.
Regardless, I trust cultured organisms (yogurt, yeast, etc.) more than the naturally-occurring ones I might find at home (particularly since I work at a hospital and might track some nasty stuff home with me). I would inoculate it with some trusted microorganisms if I was making the recipe.
With that said, the standard caveat of if it smells bad after letting it sit out it probably should be thrown out would apply. Also, although I have a degree in biochemistry I am not a microbiologist, toxicologist, or pathologist.
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Clearly, the Blendtec, "will it blend" videos, are a marketing tool designed to illustrate the power of the product, as opposed to illustrating recipes for delicious smoothies. Is it safe to drink? There is nothing here: http://www.coconutresearchcenter.org/ that I have been able to find, which deems the "woody part" inedible or unsafe. So, strictly speaking, that concoction is probably safe to drink (but I am no expert on coconut shells or pineapple leaves). The more important question is, why would you want to? I imagine the shell of the coconut and the outside of the pineapple would add bitterness and grassy flavors that would be off putting, plus, who wants to drink something that looks like that? I further imagine the texture would be somewhat uncomfortable to swallow. It just doesn't look appetizing. One of your tags is "efficiency." There are reasons that we peel our fruits and veggies, even though it may be less convenient. Safety may be one reason (maybe concern over pesticides?), but more often it is flavor and color that we are after.