This video introduces you to the Vi (and Vim) editor. Vi is the most common text editor that you will have available to you on *nix systems so it pays to at least learn the basics in case you end up somewhere where that is all you have to use. Vim is also actually a very serviceable editor which many people (mostly hardcore geeks) use as their day to day editor. We'll talk briefly about Vi versus Vim, then open a file, move around, and close the the file. Our next video will dive more into editing files with Vi.
Note: There are a lot of editors out there on various systems, notably emacs, nano, and pico. Vi is considered the lowest common denominator (i.e. it is the most commonly available one), which is why it is the one being covered in the command line basics series. It is also the editor that I use personally, so is the one I am most familiar with. Please limit editor war discussions to other threads on the internet that are meant for them.