Users typically employ "Google Dorks"—specialised search strings that filter results to show only directory listings. Common variations include: intitle:"index of" "xxx" .mp4 inurl:ftp "xxx" mp4 index of /videos/ .mp4
When you search for , you are specifically looking for servers that are publicly exposing video directories. How People Find These Directories index of xxx .mp4
Because these are often personal or unmanaged servers, the download speeds are usually abysmal, and many files are corrupted or mislabelled. The Technical Side: Why They Exist the download speeds are usually abysmal