If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Or you both have malware. LW has no other ads at all, so how likely is it that their first ad is an auto-playing video?
EDIT: And I personally see no video ads ever, FWIW.
I have this too and it started recently. It doesn't happen anywhere apart from LW. If there's malware it's something to do with LW