He's probably thinking of something like the 7.2 Trailer, but that sort of video is not the rule as far as I'm aware. Older expansions had trailers that mixed story and gameplay in cool ways (e.g., 3.1, 3.3 in particular, 5.2, 5.4). Interestingly, 7.1 had both a story video (trailer?) and a gameplay video (that they called 'preview').