In Genesis 1:6 the word translated as "firmament" seems to mean "expanse". The video then uses the story of Noah to argue that there is some magical reservoir of what over the sky. But the story says repeatedly that this is rain. Rain comes from clouds, so the reasonable interpretation is that the "expanse" in Genesis 1:6 refers to the space between the ground and the clouds.

Much Old Testament language is metaphorical, but modern religious people prefer to interpret it autistically, probably because, as Tertullian said, belief in the absurd strengthens faith. My view is the opposite, I prefer reasonable interpretations.

I can't comment on the Quran since I don't know it well enough, but I have no confidence in Sam Gerrans's interpretations.