[Mystic]

Nathanson is the creepy bald guy who was giving Walt all his instructions by phone and apparently has the capability to tap into Jack's secure lne at CTU, enabling his capture in the last episode. He's played by an actor named Geraint Wyn Davies.
I guess the "5th Hour" is the first time he's shown up, and apparently no one else knows who he is either.

[SAJ]

Thanks, mate, I'm still wondering how blind I am, or perhaps deaf.

For the life of me (and obviously I shouldn't wager at THAT price), I **still** can't place this chap by name.

Ah, well, presumably my bindness and/or deafness will be cured or cleared up in the next episode.