Oh Java, why u so sketchy?
If you’re trying to use the Screencast-O-Matic screen recording software on a mac running OS X 10.6 or higher, you’ll need to use either Firefox or Safari. Chrome will not work, as it doesn’t support the needed Java plugin.
I couldn’t get it to work on Safari, either, even after updating Java and restarting my browser. Thankfully, the program works seamlessly on Firefox – Yay, Firefox! (maybe, who knows. I might be leaving myself open for all kinds of nastiness, but I like living dangerously).
edited to add: As Sarah mentions in the comments, you can also download the program (if you have space for it #messycomputer).