It is almost impossible to crash or hang a modern browser (post circa. 2000) using EZ Math Movie. About the worst it could ever get is that you purposefully or accidentally write a loop (for loop) that runs endlessly. All modern browsers detect these endless loops, and provide a dialog box asking you if you want to get out of the problem.
Some math experiments you might try could legitimately entail for loops that run several thousands of cycles. Many diagrams that are fun to draw are like this. In such cases your browser could think that your program has an endless loop and inform you about it. The browser would ask you if you want to quit. Most likely you would choose to keep the program running, since you really want to run the loop for a long time.