As a developer/Tester I need to explain how I have fixed something or why something has broken. Usually this involves writing complicated emails with step by step instructions on how to replicate the issue.
I came across screen toaster which make it much easier to create video tutorials of what is happening on your screen. Usually you would have to install a windows application and then get this to capture video, convert it to a web format and upload it to your webserver or youtube. Screen Toaster does all of this as a web app. So just create a free account and put your headset on and you can create and upload a video in a couple of minutes. Then send a link to your contact asking them to follow your instruction on the video.
Here is one I made earlier, where I explain to a client the new functionality I have added to their shopping cart.