There are two possible explanations for this:
If you're in a country with certain licensing restrictions, we may be prohibited from displaying these videos to you.
Or, we might not have videos available for a particular team, match, or league. In this case, please recommend available (& legal) channels we could use to show videos of your team by sending us feedback (Main Menu > Settings > Send us Feedback). We will do our best to add them to the app.