To clarify I only have a couple of sample hd videos, I would like to have something longer to fully test it and I was mainly noticing the buffer while trying to view you tube videos using the app on the tv. The sample videos are only about 20 seconds long.
I do this but rather than an ext hdd I have my desktop setup with SAMBA. My 1080p Sherlock Holmes will work fine but my 720p Ghost in the Shell doesn't. It depends on the amount of compression the file uses.
You can always use Big Buck Bunny as a test file. Edit: Didn't realise I'd doubled. Sorry; Slow morning.