Oh those antenatal videos are AWFUL aren't they? You should You Tube birthing videos...they are much more realistic and up to date! Alot of them are tear jerkers though.
But yes, afterwards, there is so much adrenalin from birth and meeting your baby, the "pain" is quickly put to the back of your mind.

But with visualising, try some hypnobirthing or calmbirthing books to get some ideas in your head.