If there were two videos of the same incident, then more than one person filmed it. They would be at slightly different angles and different quality and techniques. The first job of the Police should have been to find both people who filmed the fire and verify who took the one that ended up on YouTube, and caused all the offence.
The Police did not do that, and instead prosecuted only one man, knowing that there was a distinct possibility that his film was not the one on YouTube. Incompetence or dishonesty? Either way, not how the police should behave.