Video Playback issue resolved

So my good friend John, from the first post, who motivated me to do all this, saw the post on video playback issues and immediately sent this advice:

Read the latest blog. So sounds like you are using USB drive to store the movies. The USB could be a bottleneck- data transfer is ~1/10th of an integrated hard drive. Also, it is probably a slower drive with less cache since external drives are usually for backup, not performance. I used an external drive b4 getting the server, but it was connected directly. I would try copying a movie to the main HD to see if it works. Also, in general, I would store the movies on an internal drive for playback, and back them up to external if you need to. BTW, here is an interesting overview of data speeds that I have held onto: what your computer does while you wait

i just did a search and saw this:
1). one major difference between a standard desktop drive and a dedicated Audio/Video (AV) drive is Error Correction (EC). the desktop drives run several EC routines on the data to ensure integrity, unfortunately this can chop up the data stream as it is being sent to the platters. the AV drives are designed to use minimal EC, and not interfere with the stream as it is sent in. the AV drives are DESIGNED to write multiple streams from different sources at the same time.

2). If you are using a single drive in your system with multiple folders or partitions shared (OS, misc data, video, pics, etc)then use a desktop drive. cheap and fast. if you are using multiple drives and can dedicate a drive for video then use an AV designed drive.

since I am adding a drive to my existing "home server" I purchased the following drive from Newegg. currently selling at $150

Seagate SV35.3 ST31000340SV 1TB 7200 RPM 32MB Cache SATA 3.0Gb/s Hard Drive - OEM
=======================

still seems overkill. i am sure my HP server has a pretty cheap OEM drive. works fine.

another question- what transfer speed are you getting on your powerline ethernet? not claimed, actual. you need like 25-30Mbps for bluray streaming, more like 10 for DVD. that should be no problem, but worth checking.

So I took his advice, and transferred everything from the external USB to an internal on the Mac Pro desktop. One other thing I did - I ran Maintenance 3.8 on both the mini and the pro. For those who don't know, Apple has combined the common maintenance items OS X has into one little automator file and you can download it from that link. Verify/Repair permissions, clean up cache, reindex things, etc... To be fair, both computers had a lot of clean up specifically with Plex (not surprising given all the install and uninstalls and library changes and fiddling about). Oh also, my external drive was connected to the Mac Pro via a firewire 400 and not a USB 2.0.

Bottom line, I have smooth Video TS DVD playback. Was it the internal drive move or the general clean up? Probably a bit of both. I was playing .mv4 files from the USB to the Apple TV no problem, for what that's worth. Either way, being on the internal can only help and I recommend some good clean up of your systems after you've installed and tweaked.