Isn't it his job as the elected Senator to call out Clapper on his 'lies' as he says them? If all Sen. Paul was going to do was watch the video of his testimony later then why schedule a hearing at all?
Then how do we know that Clapper is lying? We're not on the Intel Committee either, are we? At least Sen. Paul gets invited to these things, we have no access at all, so Sen. Paul is still in a much better situation to call out Clapper on what we are all so convinced are a constant stream of lies.
Sen. Wyden is on said Committee, and asked Clapper a question that, in Clapper's own words, he answered with a "least untruth" statement that was "too cute by half". This can be roughly translated as "a baldfaced lie".
Apart from that, I am personally unaware of any instances where DNI Clapper has publicly lied.
Additionally, DNI Clapper appears to only answer prepared questions (i.e. forwarded to his office prior to the discussion). I'm not sure if this is standard protocol for Congress, and for obvious reasons I also don't know if this applies to private briefings.
Certainly you'd send a list of prepared questions if you were holding a hearing to get answers. Otherwise the guy might be able to plausibly claim that he doesn't have the details and would have to get back to them.
If you're holding a hearing just to ask a trap question on camera then you might deliberately not send prepared questions, but I would like to think my elected representatives have more respect for people than that.
This isn't to say he left early, only that he left. Meaning he attended at least part, which is more than we can say about virtually anyone else as names don't appear to have been released yet.
Presumably leaving out of disgust for Clapper's lies; but the media will leave it short like this to make it seem he's marginally apathetic.