Successful DR4Bs have a lot of components that can be hard to learn, but here is a link to a post that will be able to answer most questions about them, along with a step by step build guide. One specific thing I noticed in the video, was the fact that the top four bar is longer than the bottom four bar. This will not make the lift lift vertically, which is one advantage of DR4Bs. This, and much more, is covered in the post linked above.