I believe that video has no value as the only method, or as the first mode of learning. If he is working with a good instructor, and is using video as a reference when working on material that he has already learned from that instructor, then I believe it can be a valuable tool.
The fact that he is a sandan, and at least SHOULD have a solid foundation and knowledge and skill in his current system, is what makes me say that he has no need for this. He's already ahead of the game and what potential the video MAY hold has little value for him. If his skills are so poor that he actually needs this, then his problems are bigger than finding the "right" video program. He needs to start all over with a good teacher instead.
The way he applies his foundation in his current system may be significantly different from how the video expects him to do it, how a different kenpo system expects it. Different systems can do basic things quite differently. Applying the foundation of one system to another system is no guarantee that it will work.
If one is solid with his system, it is possible to use video to get examples and ideas, that MAY be translatable into the base system. There's nothing wrong with looking at video for this purpose, if you are taking these ideas and deliberately adapting pieces to what you already do. But this is cherry picking with a deliberate purpose and he needs to be clear in his own mind as to what his intent is.
If his intent is to systematically learn a whole kenpo system, then it's a bad idea and his background dictates that he doesn't need it and it's a waste of his time.