Filming is legal. In public spaces (streets, parks), there is no "reasonable expectation of privacy." You do not need permission to point a camera. The exceptions are usually for offensive or harassing type of filming.
Publishing is regulated. In EU, once you share the footage , you are "processing personal data" under GDPR. There are also exceptions where publishing without permission is legal. Legitimate Interest (security footage or incidental background), Public Interest/Journalism, and Artistic Expression.
Generally you must ask permission to publish, not to film. Although asking permission to film is good ethical principle too.
Filming is legal. In public spaces (streets, parks), there is no "reasonable expectation of privacy." You do not need permission to point a camera. The exceptions are usually for offensive or harassing type of filming.
Publishing is regulated. In EU, once you share the footage , you are "processing personal data" under GDPR. There are also exceptions where publishing without permission is legal. Legitimate Interest (security footage or incidental background), Public Interest/Journalism, and Artistic Expression.
Generally you must ask permission to publish, not to film. Although asking permission to film is good ethical principle too.