You would be better served to join a retriever club, or work with a pro, or somehow find a mentor who knows what theuy are doing to guide you. Training is a hands on discipline.
If you want a DVD, I would look at the accomplishments of the trainer.
There is absolutely no comparison between Lardy's results and Grahams.
Lardy has trained scores of Champions, including more National Champions than anyone in history. Whereas Graham has never titled a dog. I believe he has only a 4th place finish in his entire career.
I don't think DVD's are much use, except maybe Lardy's CC Video. However for a beginner, I think that Lardy's collection of RJ articles Volume 1 is PURE GOLD
"So what is big is not always the Trout nor the Deer but the chance, the being there. And what is full is not necessarily the creel nor the freezer, but the memory." ~ Aldo Leopold
"The Greatest Obstacle to Discovery is not Ignorance -- It is the Illusion of Knowledge" ~ Daniel Boorstin