Handstand One purchase

If I purchase handstand one on my smartphone, can I use it on my smartphone? Is the only way I can do it right now.

You can use it on whatever you have internet access on. It's a web based program.

The videos might not work with some of the different browsers though.

It works fine on the default browser for my Galaxy S IV. You can undoubtedly download other browsers with which it is compatible if it doesn't work on your phone's default.