How to go about obtaining large amounts of obscure data? I apologize if this is the wrong stack forum.

I want to obtain a large amount of surveillance data for a computer vision project I am working on but I am having a difficult time doing so. I specifically am creating a project that would more so work with a governmental surveillance system that monitors public places (like people walking along the sidewalk, cars driving by, etc.) so I'm thinking like the CCTV type of footage.

Youtube has failed me, and my professors aren't sure either. I was wondering how someone might go about this, and more broadly, how other people have coped with obtaining a large amount of obscure data for their own projects.
I do not think that there is a general strategy to obtain obscure data other than:


Think about who might have such data (legally and ethically).
See whether they provide this data for free.
Ask them.


You may have luck in crowdsourcing steps 1 and 2 of this process on Open Data Stackexchange, half of whose questions are data requests. However, given the nature of your specific enquiry, I doubt that you will be successful there, as such data is very unlikely to be open.