Graphics cards are important to enhance your viewing experience on your computer or laptop. These cards improve the texture and dimension of the picture on your screen. If your laptop does not have a graphics card, it does not mean that you will not be able to view anything. It is just that a card is dedicated to the graphics and picture quality of whatever you are viewing. If what you use your laptop for has nothing to do with pictures, movies or images, then there is no point in getting a high-end graphics card.
For video editing, a couple of things need to be borne in mind:
Rendering: Rendering is the addition of saying lamination, texture, color, shading etc. to a 2D or 3D frame to make it more lifelike or realistic. This helps especially when you are working with say games or creating animation or movies. The rendering capacity is drastically increased when you have a discrete Graphics card installed in your laptop. Typically, where there is no Graphics card, the CPU does the rendering and there is a marked difference in the quality and effect you create.
Technology: Technology has not remained constant and with advances, we are seeing better pictures and better movies. IF we are to consider making movies or videos that are to be viewed by people or you in 4K, we must think ahead while editing as well. Using the latest technology and software will help you to create the best quality videos.
There are two manufacturers of graphic cards: NVIDIA and ATI. While these maybe just the top two, video editing itself needs a very balanced approach. By going hard and heavy on one aspect of your laptop may help, you may not have the budget or scope for other important components of such laptops. So, research well and know that the best laptops for video editing always use a balanced approach to equipping the laptop with all the right components to make editing work a breeze!