After posting a link to one of my vids I decided to try and understand whay it wont play for some people on phones etc .
I found a good ( I think) explanation ;
Why are some YouTube videos not available on mobile devices? | Pocketnow
All to do with adverts/ music and making money or not as some devices don't show the adverts that generate the revenue that pay for the site and make the money .......
Hope this helps - its not down to the person posting the vid - more the attitude of those who make the music that goes on them.