I’d recommend acethinker screen grabber online to you, It's a a web-based application, no need to download or install any third party software. Cross-platform which mean you can use it on both windows and mac. More important, it’s totally free.
Hi, I know a very fast way how to record computer screen. Try Movavi Screen Capture Studio. My friends gave me that idea s few months ago and now I pretty happy with it. I personally use it to save screen clips in any format for my online projects. Highly recommended