Then essentially descends into a variant of solipsism, where he says all the theories are just filtered through our consciousness (true), so cannot be correct.

The limits of human mind are something we must acknowledge but they aren't something that should make us jump to "everything we know is wrong!" -mode. There is some uncertainty in everything we claim to be true, but are the uncertainty factors really that meaningful.

To know that our consciousness is the exact distorting part in the equation (="everything that goes through our consciousness is fundamentally distorted"), we should be able to see the world outside of our consciousness. Can we do that? How can he point the problem being in consciousness when he doesn't know how the world looks like outside of it. The problem lies in consciousness because consciousness essentially distorts everything, or..?

I think reasonableness is the word we need here. Before jumping to extreme conclusions, it's good to think: "Does this really mean what I think it means? Could I have some sort of a pre-existing bias that affects what kind of proportions I give to this issue?". I think he's doing that, giving arbitrary proportions to things.

Scientific method is designed so that the subjectivity of researchers would be minimized. And yes, applied sciences are great example of scientific theories in action. Theories don't need to be 100% true for them to be useful/close enough.

I once read a nice conceptualization of the process of testing theories. At first theories are blurry, but experiment after experiment the image becomes more clear. There can be some stumbling blocks in the way and not one experiment is perfect, but if after many, many experiments the results point to one certain direction, then we know better that there is something in there.

Let's not go to the thought experiments that perhaps our world is actually a miniature controlled by aliens, or something similar.... even if that was the case, this miniature world is currently working in the way we interpret it. Our interpretations are the best we can say at the moment. If one alien now stepped on the miniature, things would be very different, of course :P

It's funny these kinds of "what if..." thought experiments are sometimes taken very seriously, as if their slight possibility would discredit everything, but actual hard work on theories is dismissed.