Hi;
The Good:
Liked the experimental way the value of Pi and the formula for the circumference was approximated as the best way to introduce the concept.
The Bad:
Not enough demos to illustrate the product correctly.
The Ugly:
Never, never, ever, cripple any product in any way for your demo. That ugly watermark, smack dab in the middle, interferes and ruins the vids. I or anyone I know never purchases a product that we cannot see in it's entirety first. Crippled software aggravates the heck out of me. Do a time trial on a limited number (more than 2) vids, no ugly, distracting watermarks.