What's a good entry-level text/video on residential plumbing?
Home Depot and Lowe's both sell pretty well illustrated, basic books on Plumbing.  I have one, "Plumbing 1-2-3" which is from one of those two (can't remember off hand which but I think it's HD) which covers all the basics, has clear pictures, easy to follow directions, and makes you think, 'Oh heck yeah that's obvious...'

As for videos - there's always the DIY network Plumbing section.