Do camera companies pay some people to post about their gear? Just curious.

Short answer...yup. Social media marketing is an increasingly important component of the overall advertising mix. TV, radio, print, billboards, product placement in movies, and now social media of various types. I won't say all companies do, but I'm told it's all about creating a buzz and discussion about products. One company told me they used social media for damage control when one high-end product failed to deliver.