I've watched many videos and read many PDFs from DFL, and they are very helpful in getting to know how to use their tools (and a little about data recovery in general). My only complaint with their videos, is sometimes the speed is too fast and the player doesn't have a feature to reduce the speed (depending on the encoding used). Also, it would help if all of their videos were narrated (by a native English-speaker), and came with matching PDFs that explain what they have illustrated in the video. They are marketing primarily to people/businesses just getting into data recovery, whose market or circumstances do not justify the major investment required for a PC3K, DDI4, proper training, etc. Combined with their forum, I think they do an excellent job of addressing their target market. Their products are far from perfect, but also not as bad as many suggest. At least they try very hard and are committed to improvements and fixing bugs.
You can mock and ridicule all you like, but I don't think that's very helpful or professional. They meet the needs of many people like myself and for that I'm grateful.