Flash & Videos on Portfolio Press?

Without looking at the theme itself, I think what they use is a widget or some shortcode for displaying an image gallery in a specific format. I would doubt that there’s an easy way to do it.

The easiest way is to install the options panel and disable the automatic display of portfolio images.

Then, insert the video on the portfolio post (like you would for a video you wanted to display in a regular post- use the Viper Video plugin if you need one).

You’ll still need to upload a thumbnail of the video as the featured image though, so that there is something to display on the main portfolio page.