It is able to snip free-form, rectangular, window or full screen and allows you to draw in freehand, a highlighter and an eraser. Windows 7 comes with a very simple screenshot capture and image editing tool called Snipping Tool. You can take screenshots directly in Windows and save them as image files by pressing the Print Screen button on your keyboard, run Microsoft Paint, Wordpad or Microsoft Word, and press Ctrl+V to paste the screenshot to the program which can then be saved.
Moreover it requires more time and effort to edit the video and upload it to video hosting websites. Although capturing a video is so much better, but it involves using a software that may be a bit difficult for basic computer users to use.
Hence having a screenshot is very useful because it can be treated as a proof of something that you saw, for example a rare error message that happens randomly or even a website that is being defaced by a hacker. Describing an occurrence using merely words is sometimes not enough for other people to believe what you said.