It's recommended to try out the demo before purchasing, but as far as I've seen, the demo is bundled with the full paid package.

That kinda defeats the purpose of a demo, no?

The playable Web Demo is already available for free right on this page so you can test all the features and UI performance instantly. The file bundled in the paid package is the 'Sample Project' (source files) meant for buyers to check the backend configuration and parameter setup. Giving that away for free would completely defeat the purpose of selling the plugin.
Edit: I've switched to having people download the Test Demo for any similar questions.
Edit2: Due to the risk of plugin leaks caused by existing project decryption tools, it is mostly up to you to review the images and YouTube clips to make a decision.