or why we always perceive what we already know?

no one can claim to be in possession of some absolute truth.

Is this absolutely true?

By definition you could not "own" an absolute truth, since being absolute it would stand on its own. Once you claim ownership, it changes into something else.

I think Rowe is expressing an opinion, making a 'claim'. The last sentence of the clip talks of 'our' ideas, perceptions etc., all of us. Her point is that if we accept our nature in this respect, perhaps we would fall less in to the trap of claiming absolute truth. Note that she does not deny (or assert) the possibility of 'absolute truth', only as ratifar points out, the 'ownership of such truth.

(I think too, there are fairly basic epistemological arguments about truth value that could be raised.
I have clipped four or five things in the last two days that hint at the limitations of language, or language as a 'trap')