The narrator mispronounces foliage every single time. It has three syllables, not two.
> The disyllabic pronunciation \ˈfō-lij\ is very common. Some commentators insist that foliage requires a trisyllabic pronunciation because of its spelling, but words of a similar pattern such as carriage and marriage do not fall under their prescription. [1]
The speaker otherwise has a fairly General American accent, so I'm curious if the two-syllable version is a geographic thing? Unfortunately, it was never included in the Harvard Dialect Survey [2].
MW does also note that that pronunciation is nonstandard.
I checked the first 20 samples on youglish ( https://youglish.com/pronounce/foliage/english/us? ). 16 used an unambiguous three-syllable pronunciation, 3 unambiguously omitted the middle syllable (#9, #16, #22†), and one (#12) was ambiguous. Of the disyllabic pronunciations, only #9 had a marked regional accent.
† Why is #22 one of the first 20 samples? Two of the earlier samples are different timestamps into the same video, which I only counted once, and one is missing, which I counted zero times.
Yes, that's how you get pronunciations that differ from the spelling.
If a word is rare enough, its pronunciation will be regularized to match its spelling. And for a foreign speaker, almost all words are that rare.