The man says it himself. He is explicating what someone means (whether they appreciate it or not) when they speak of evidence. They take a piece of information to be evidence in favour of a proposition if and only if they are more willing to accept the proposition already believing the piece of information than they would be otherwise. He is not so much declaring what evidence is supposed to be than what it is we mean when we speak of it.
No, of course it is for many not comfortable to admit, or indeed to be told that what we hold as evidence is really just what ever makes us more credulous rather than anything vaguely implicative of the proposition in question. But he is not wrong. We do not have access to "truth" beyond the purely formal. While reality - again, to the extent that there even is any such thing - wouldn't much care about what we think of it, what we think of it is the only thing we have any chance or reason to care about, and so what ever we argue, no matter how closely we believe it tied to the external world, nonetheless does not become an argument until well after we process it internally.
If I had to pick one thing that bothered me most or at all about this explication, it'd have to be the liberal use of the notation from probability, when all he is speaking of is mere individual credulity. Too many are too happy to conflate the two and I myself was about to mistake his meaning for the assertion that E is evidence of T if even to merely believe E renders the truthiness of T more likely, when he is saying nothing of the sort.
Better to leave questions unanswered than answers unquestioned
