I think you are mistaken. In Germany public photography is legal as long as it is not your intend to photograph/monitor individuals. They can totally be part of the image, just not the focus. Videos are also legal as long as it is not targeted or constant indiscriminate monitoring.
I don’t think other EU countries have largely different laws given how common dashcams are.
Police officers? The main issue here is that those laws are about balance. Balance of your rights and the persons’ you are filming. There are some general rules and a large grey area.
In general your vlogging isn’t an issue. However, if you knowingly start recording a specific person e.g. a busker, or in your case a street scammer, things become more difficult - especially because you are vlogging. The expectation that you are going to upload the video makes it unlikely that you are just recording for evidence.
I am not a lawyer. I think the police promarily tried to de-escalate here.