I don't think any music video has come even close to having the impact the Thriller video had. When it first aired back in 1983, it blew everyone's mind, not only because it was Michael Jackson at his best, but because of the production value of the video. It featured the voice of the Master of Horror himslef, and was directed by a bona fide Hollywood director who has to his credit Animal House, An American Werewolf in London, Blues Brothers Trading Places, Coming to America, among others.
Good call on the best video that encapsulates the 1980s! I would've suggested Video Killed the Radio Star, which was the first video played on MTV when it launched....but most folks probably weren't around to see that. The MTV audience grew exponentially after first launch, but probably only a minority saw that first video, and upon repeat (there was a lot of that in the earliest days, until artists starting producing videos specifically for MTV) it wasn't a big deal. It was just FIRST.
Anyhoooo....I digress....I would've said Video Killed the Radio Star, but I'd like to switch my vote to Thriller. If you take a poll about 80s videos, that one is ALWAYS going to be mentioned frequently! Good call!