Hi,
We tested this here but could not reproduce as the mp4 loaded and played fine.
Did you add the necessary JAR files to your project? See here: Knowledgebase: JAR file dependency for Android devices (Android support for FMX applications)
If you added the necessary JAR files and the video doesn't show up:
- Which mp4 URL did you use so we can test with it?
- What is the version of your IDE?
- Which Android version do you have?