solved this myself. below my solution. If that doesn't work for you call support: ask them to reset/ensure permissions allowed. (When that didn't work for me -- I looked closer at my source. Hah!
I compared the (working) "public" video html to mine.
I found I was elementizing "< src=..." src is an attrib of <video>, not a sub-element (is that even a thing?).
My fault for trusting the example I started working with -- it had src as a (sub) element (and wasn't even closing the <video element:
look at option 4 for HTML5. hah, hah hahhahahaha!
so the correct html5 is:
<video width="720" height="405" controls poster="images/Start.jpg"
src="vids/mine.mp4" type="video/mp4" >
Your browser doesn't support HTML5