Absolutely love it - especially the bit about not being frightened of not knowing everything. Very cool! I had seen this clip a while back - but its great to see it again. If you want to see more of Feynman (I highly recommend it), check out clips from The Pleasure of Finding Things Out (which is also the title of a collection of excellent Feynman essays).
Update 4/6/10 : Bulent pointed out this short clip from Feynman and it is too good not to include it here. So here it is: