Have seen a very recent report on here from someone in USA saying their State Law somehow requires blocking a part of Pornhub & others, so geo blocking happens,

I sometimes get a YouTube system message saying "Video not available in your country"

.

However, with your short vids,make sure you're not selecting the wrong "https-mp4's".

Could be there are similar lines of code for trailers and main vid.

Use that Ctrl+f again to highlight all instances of ".mp4"

Then carefully check each lines details,

esp "contenturl" and/or words like thumb/trail/teaser/main/sub///

.

I just tried it again, and this time couldn't even get the correct page of code,

it's critical where the "View PageSource" thing is referring to, poss u clicked on a thumbnail or trailer ??

So many variables...given me brain-ache, better to float downstream than battle upstream against a computer problem.