Promotional videos and video advertisements that contain Miis
This is a list of all the promotional videos and video advertisements I can find that contain Miis (very incomplete at the moment). For the sake of simplicity, I'm only counting videos that feature Miis prominently and/or as a major selling point. I will also be excluding videos that are strictly gameplay clips/footage with no extra content added (extra content being things like pre-rendered animations, vioceovers, real life clips etc.) interviews and guides, as I believe they belong in separate categories.
Wii
Wii Music Korean Trailer
Nintendo Wii Mii Channel Korean Trailer
Nintendo Wii Mii Channel Korean Commercial
Nintendo Wii Mii Channel Korean Commercial 2
Wii no Ma Channel JPN Commercial
Mii stamp commercial
[CM] Shuzo & Sanma tries Mii Maker [Wii]
Mii Making Japanese Commercial #1
Mii Making Japanese Commercial #6
Nintendo Wii Check Mii Out Channel JPN Commercial 2
Nintendo Wii Check Mii Out Channel JPN Commercial 3
Nintendo Wii Check Mii Out Channel JPN Commercial 4
Nintendo Wii Mii Channel JPN Commercial
DS
Minna no Nintendo Channel - Connection Ambassador Trailer
Minna no Nintendo Channel - Tomodachi Collection - Making a Mii Part 1
Minna no Nintendo Channel - Tomodachi Collection - Making a Mii Part 2
Minna no Nintendo Channel - Tomodachi Collection - Using Miis Part 1
Minna no Nintendo Channel - Tomodachi Collection - Using Miis Part 2
Tomodachi Collection JPN Commercial
Tomodachi Collection JPN Commercial 2
Tomodachi Collection JPN Commercial 3
Tomodachi Collection JPN Commercial 4
Tomodachi Collection JPN Trailer
3DS
Nintendo - Tomodachi Life Music Videos Starring Nintendo Developers
Tomodachi Life Direct (US) 4.10.14
Tomodachi Life Direct (EUR) - 10.04.14
Super Smash Bros 4 (3DS) AKB48
Super Smash Bros. for Nintendo 3DS - Mii Fighters Attack!
Wii U
Wii U - New York Mii Invasion
Nintendo - The Miis take a snow day at Whistler Blackcomb
Wii U - A Very Special Day in Canada For The Miis
Super Smash Bros. - Mii Character Announce Trailer - E3 2014 - Eurogamer
Nintendo Switch
Miitopia - Announcement Trailer - Nintendo Switch
Miitopia - A Pretty Barn Good Overview Trailer - Nintendo Switch
The Game About Playing With Roles - Miitopia Trailer - Nintendo Switch
Miitopia - Miitopia Makes Over Mii Characters Trailer - Nintendo Switch