You can now click the Start Recording button and start your screencast. When you’re done, you can click Stop Recording and you’ll find your screencast at the file you selected. Speak into your microphone as you record the screencast and OBS will add your voice to the video file.Read Article]. The video file OBS creates is an H.264 MP4 file at the resolution of your desktop. If you’d like to edit your screencast and remove any unnecessary bits, use Avidemux to edit the video file. It’s a simple, free, and easy-to-use tool for doing some basic video editing.