SD video is the 480x640 resolution while the HD is the bigger size like 1080x1920. My Samsung phone has a good camera that is HD. When I took a video and inquired about editing, a colleague said that I would need a newer video editor that is capable of editing HD videos. So that's when the SD came into the scene, I learned that old editing software can handle only standard video. My question now is this - if the HD is for the wide screen like the moviehouse showing, I do not need it because my purpose is to play it only in the computer. Am I right on this or should I just pursue the HD video even if I don't need the HD resolution?
The "HD" standard is specific to a 16:9 ratio, which with extremely rare exception, includes phone, TV, and all computer screens made in the past 10 years. "SD" is a 4:3 ratio, which is the boxier style common with the long-obsolete CRT screens. So if you have a really old computer and you only want the video for yourself, you should go 4:3, otherwise go 16:9.
The important things to know is that all screens are now 16:9, and HD is always 16:9, however not all 16:9 resolutions are HD, with such exceptions being 2k, 4k, etc. So whatever you make should ideally be 16:9.