In reviewing various screencasting, video, and audio tools I find that Quicktime is reliable alternative to Screencast-o-Matic and the recording capabilities that can be found directly on Google's YouTube. Below is a brief description for each of the tools as mentioned above.
Screencast-o-Matic has a free version in addition to low priced Pro version. The free version provides 15 minutes of recording time and makes all your recordings available to the public via their website. You may download and share the permalink to the screencast you recorded. Audio can be recorded with the free version however to annotate and provide webcam recording you will need the paid version.
Quicktime provides a great alternative to Screencast-o-Matic. Quicktime is available on both Windows and Mac operating systems via download. With Quicktime you can choose from a movie, audio, and screen recording. What is great about Quicktime is you can easily edit and trim your completed work before exporting and sharing. You can save the raw file in various formats or you can upload it directly to YouTube after editing.
Just as YouTube may be restricted and unavailable at certain workstations whether at school or in the workplace, you can rely on the web-based tool, Screencast-O-Matic. Quicktime must be installed on your computer in order for it to be beneficial to your needs. I choose Quicktime as my go-to tool for screencasting and audio recordings. For my students with limited access I suggest Screencast-o-Matic. Give all three a chance and choose what works for your everyday situation.