Documentaries with sound effects seems very dishonest to me.
It's pretty much necessary, and nigh universal. It's very hard to get good quality audio recording in the field. Fun fact: the planet earth crew carried no audio equipment at all, and added everything in later.
What's really dishonest is using rented animals, which is very common, especially in "wildlife" photography.
As for spiders, the issue isn't so much taking in the gas, but distributing it. Arthropods have an open circulatory system, meaning they have a heart like pump, but it is like an aquarium motor, and just keeps things mixing. This works alright at their size, but doesn't scale up well. Insects have their tracheal system, where they basically have tubes that bring air directly to the tissue that needs it, which allows them to have higher metabolic rates than things like spiders.
Another issue for spiders is that they lack limb extensor muscles, and use hydraulic pressure. This is why jumping spiders have ordinary sized legs, unlike pretty much every other specialized jumping creature. I suspect that if you scaled that up, the pressures required would be formidable, and might pose problems.
True. By metabolism, I meant the oxygen metabolism... Of course, that isn't technically a correct use, either, but insufficient O2 to breath is what I was meaning.
That is actually the most correct use.
Also, all spiders have lungs of a sort. In some cases, they don't have book lungs proper, but they still have a hollow cavity where they would otherwise be, which they use for gas exchange. Some other arachnids don't have any lung like structures, and do gas exchange through the skin, but that's mostly mites and harvestmen.