"Advanced Handloading" by Wolf publishing (host, John's Barsness), Sierra's handloading video (host, David Tubbs), RCBS's handloading video, in that order (Best-to-good).
John Barsness is the best for informing providing you "guidelines" to get the best accuracy (e.g., bullet runout, case neck thickness, etc.), David Tubbs goes into more detail/explanation and covers some topics not covered in the Barness video (use of hornday OAL guage; adjust resizing dies to match one's chamber etc.). The RCBS video is best for showing you the basics.
If I had to get one, I would get the Barnes video.