A mirror site is essentially a 1:1 copy of the original website. In the context of EZTV, mirrors scrape the original database of torrent files and magnet links. When a user accesses a mirror, they are interacting with a visually identical interface, but the underlying domain and hosting provider differ from the original.
When you use an unofficial proxy, you are routing all your traffic through an unknown server. The operator of that server can theoretically see every piece of data you send, including login credentials, search queries, and downloaded file requests. They could inject their own malware, ads, or tracking cookies into the page. eztv proxy list