A series of free Calculus Video Lessons on Vector Fields.
This video gives the definition of a conservative vector field and the potential function. There are links to many common types of problems related to conservative vector fields towards the end.
This video gives the definition of a 2d and 3d vector field, and does one example of roughly sketching a vector field.
This video gives a theorem to show that a vector field on R_2 is conservative. It then proceeds to work 3 examples, determining in each if a vector field is conservative or not.