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I stopped watching after it claimed that St. Thomas believed in flat earth, attempting to support this lie with distorted out of context quotes.

Except that the video never claimed that, just citing what St. Thomas believed in a solid firmament with waters above it, and said that this was consistent with the FE cosmology ... i.e. flies in the face of NASA cosmology of the ball floating around in space.  You appear to be very educated, but I often see a lot of sloppy thinking and poor logic, where you conflate things.  You often cite St. Thomas as your authority for ball earth, but then you don't accept what he holds regarding the firmament.

It would be interesting to map out what St. Thomas' cosmology might look like give that he did believe that the earth was spherical, and yet that there was a solid firmament above it.  I'm guessing that in his view the firmament surrounded the entire earth, but that within the firmament you had the spherical earth.  He also wrote about how this entire thing earth + firmament was suspended in the middle of the waters.

I have a feeling that some of these thinkers felt that the earth was spherical but then denied that there was solid land down there or at the very least that there were inhabitants on the underside of the earth.

See, here's the thing.  Church Fathers and Medieval thinkers did not have a concept of gravity.  So what, then, would cause people to stick to the bottom of a ball?  In fact, one of the early cosmological debates among the waters was how the earth, firmament, i.e. the world could be suspended in the waters without "sinking" to the "bottom".  That's why some held the world was hemispherical in shape, because the land would sink to the bottom of the water-filled cosmos, being heavier than water.  St. Augustine thought it was tenable since even if the world were at the bottom-center of the universe, that would still be considered the center (note his assumption that the world must be at the center of the universe).  Others posited that there was some rotation in the universe's water that kept the earth suspended.  But for them up was up and down was down, so they didn't have some notion of gravity that would cause people to stick to the bottom of a ball.

Please provide unmistakable proof that St. Thomas Aquinas believed earth is a globe.

Do you have an explanation for the firmament/dome Thomas believed in and how it fit over a globe?  Can you also explain where the waters above the firmament can be found on a globe? 

The guy in the video made an assumption based on Aquinas' belief in the firmament as well as his respect for the flat earth Fathers of the Church that went before him. In fact, that this Protestant sourced from the Fathers of the Church because he recognized they largely believed the same as each other is quite surprising--good eye from a Prot.   

Although, if I remember correctly, the quote from St. Thomas isn't 100% clear proof that he believed in a globe I'm inclined to believe it is much, much more probable that he did. I don't remember the exact quote but it's like he assumes the globe was proven in a conditional statement I think.

Although, if I remember correctly, the quote from St. Thomas isn't 100% clear proof that he believed in a globe I'm inclined to believe it is much, much more probable that he did. I don't remember the exact quote but it's like he assumes the globe was proven in a conditional statement I think.

He basically cited Aristotle's proofs, including the old ship sailing over the edge, aka disappearing from the bottom up.  But he did also believe in a solid firmament that kept waters off the earth.  So it's somewhere in between, as I posted above.  It's neither NASA's space ball, nor is it necessarily the typical FE model, but something in between.