You can include videos on the opt-in & share widgets/pages you create using UpViral, which can be added inside the visual editor (when you are editing your opt-in or share page).

Here's how to add a video to your pages:

Step 1: Double click on text inside the editor to reveal the menu.

Step 2: Click on the video icon.

Step 3: Add in the URL of your video (e.g. YouTube video link).

In case you want to replace a current video with another video: 

Step 1: Click on the video.

Step 2: Click on the "Replace" icon.

Step 3: Add in the new video URL.