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?
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.
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.