as reported by @Doc_James, webm media not playing on iOS safari.
To replicate: on completely updated iOS device open Safari and go to https://en.m.wikipedia.org/wiki/Pneumonia and click to view first video (looks like this)
It appears to open up a new window with the file page: https://upload.wikimedia.org/wikipedia/commons/8/8e/Pneumonia.webm, but the page is blank
Appears as a downloadable file icon in chrome on iOS. Opens up player and plays in chrome on Android.