As of now, Bing is flagging the VLC homepage as "dangerous." More specifically,
Bing says the site has "indications of malicious activity," was scanned "16 times over the past 30 days," and that the last scan was on November 25, 2018.
Techdows, who spotted the warning, did some digging and found that the warning is likely related to a security vulnerability in old versions of VLC that
Microsoft disclosed earlier this month.
The VideoLAN team doesn't understand why Microsoft is flagging the site, as they claim the files on VLC's homepage are correct.