Error: Attribute webkit-playsinline not allowed on element video at this point.

HTML validator error message

Error: Attribute webkit-playsinline not allowed on element video at this point.

Cause

That webkit-playsinline attribute is necessary for older, than iOS10 devices to prevent videos in our slider going fullscreen, which is a lot of currently used devices so it wouldn't be a good idea to remove it. The html validator might sees it as wrong, because from iOS10 it was implemented to not to be necessary, but it is necessary, so you should ignore the error message.