I used this to make my videos here on XenForo. Allows you to add sound tracks and even video voice overs. Easily uploads them to YouTube. Xomes with an in-built video editor where you can split your recordings and add text in between two clips, creating a slideshow effect.
Free with the option to purchase a lifetime license or uninstall it after 30 days.
I have captivate and tons of other software as well as external hardware for recording and editing any source, but when I am doing something fast and simple and am not inserting menus, overlaying text or images or adding secondary audio samples into the mix, I use this exclusively. It is simple to use and setup, opens instantaneously, works quickly and flawlessly and really saves a bunch of time when I am not needing to use something really high end with every option known to man.
It not only captures video from boxed regions to full-screen, it also can snap images in full screen (while open the print screen button automatically snaps and opens up the image editor by default but can also be set to auto save it to an image file as well as send to print queue, email, ftp transfer or the a bunch of the apps from the office software suite) as well as objects, windows and scrolling windows like when you have a webpage that scrolls down for 10000 pixels..you can also set it to freehand capture a region which is cool but I don't really use it as I just manually blur things that I don't want people to see.
There is a lot of other functionality as well but I figured I would point out some of the basics of the app since I use it and I like the way that company does business.