No yet i have done what you have said though and i get the movie to play but it buffers for ages, then stops then buffers again.
is there a way of adding advanced setting to increase the memory.
Normal videos play fine SD if i drop the HD formate to 720 or lower it plays then.
I am going to post the issue on the plex forum to see if any one has solution. it could be My mycloud as its only basic. but from the testing I have been doing at least i know its not the file itself.
I will keep tinkering with it if i get it working i will let you know.
Once again thanks for your help