Describe the bug
Apologies in advance for this less than stellar bug report. In #19322509-hc user reports their MP4 video doesn't play on iPhoneX, Safari and explains:

my mp4 files plays on normal browsers but not on iPhoneX, the browser specifically need an option "playsinline", which I couldn't set when i insert the video.
if i add plays inline on an html i created, it works
but i don't see such option on the WP video plugin options

To Reproduce

Steps to reproduce the behavior:

1. Go to post/page editor
2. Add a video block
3. Add Mp4 video (Autoplay on, Loop on, Muted on, Playback Controls off, Preload auto, no post image, AMP layout default, AMP noloading off)
4. Visit with iPhoneX using Safari. See just an image, no video.

Video specs:
Format: H.264 HD (1-1-1)
Resolution: 1024x768 4:3
Encoded FPS: 30
Data size: 5mb
Data rate: 3.15 Mbit/s

Expected behavior
Expected the video to play, or at least have an option to tap to play

Screenshots
Apologies, none available, don't have the same device to thoroughly test.
Not an issue on Android with Firefox

Smartphone (please complete the following information):

• Device: [e.g. iPhonex]
• OS: iOS version is 13.3.1 and iPhoneX

Couldn’t get the safari version

• Browser: Safari

Additional context
Followed up in #2781652-zen