I recently watched a video by Rick Bennett head coach of Union College that describes his approach to defensive zone play. I found the DVD to be a well designed approach to the concepts needed to teach your team the proper approach to playing as a team as well as individual tactics needed to be successful. The video is about 40 minutes long and has a number of drills that you can use to work on your teams approach to playing defense.
Coach Bennett also utilizes his goalie coach to talk about what the goaltender should be doing during the play to stay involved and to communicate with his teammates. I think this is a very well spent $29.99. I suggest if you have questions about defensive zone play you should buy this DVD and learn what Coach Bennett is teaching.
On a personal note, after watching the DVD I had a few questions and I emailed Coach Bennett with those questions and within a few hours he replied with answers and an offer to speak with him directly. How often do you get the chance to interact with a DI head coach? I suggest you buy this video and give it a good look.
Here is a link to the website where you can purchase the DVD.