Well mine came with a DVD...but at best it's described as just okay...it's not specific to yorkies. Actually my video included NO yorkies in it at all. It just provided various demonstrations of different uses of the clipper and combs. I could however cut a pom pom tail on a poodle now if I wanted.
There are lots of grooming videos on youtube.
My clipper blade is adjustable...when adjusted it varies the length and width between blades...and then you add the combs.
If you aren't planning on trimming all way down...the oster is probably all you need.