The first thing to check are your Party in my Dorm settings to ensure they are all turned on and properly set.

In your Preferences tab, turn on the "Enable Video Rewards" toggle. You may also need to toggle "Use Mobile Data for Video Rewards".

Please keep in mind that video ad availability can vary depending on your geographical location, the type of device you're using and many other factors that are determined by the third-party company that manages it.