Moving the poster image into the video tag works better for html5 videos

[acwolff]

@sachinchoolur in issue #1380 I reported a problem with the poster image on an iPhone: the poster image disappears on an iPhone.

I did use the code you proposes in codepen https://codepen.io/sachinchoolur/pen/ExXxqPe where you set the poster outside the video tag, like this:

<a class="gallery-item" id="s0"
data-video='{"source": [{"src":"slides/IMG_0877.mp4", "type":"video/mp4"}], 
"attributes": {"controls": true,   "playsinline": true}}' 
data-poster="slides/IMG_0877.jpg" 
data-lg-size="608-1080"
data-sub-html= ''>

This gives problems with the poster image on an iPhone.

But if I change it into

<a class="gallery-item" id="s0" 
data-video='{"source": [{"src":"slides/IMG_0877.mp4", "type":"video/mp4"}], 
"attributes": {"controls": true, "poster": "slides/IMG_0877.jpg",  "playsinline": true}}' 
data-lg-size="608-1080" data-sub-html=''>

the problem is solved, see my test album.