I always create screencast with a web-based software calls Acethinker Online Screen Recorder, free and works fairly well. And here are the steps to record computer screen with it.
Step 1. Run your web browser and visit Acethinker Screen Recorder website, you can google search for it. This app compatibles with IE, Firefox, Chrome, Safari, Opera, etc.
Step 2. Click 'Start' to open the screen recording app.
Step 3. Select the recording mode you like, Full screen record or Region record.
Step 4. Click on the red button to start the screen recording.
Step 5. Once you stop the recording, you can click on "Show in folder" to find the recorded video.