I have noticed something similar/the same when playing files over my home network. if the server becomes busy (like when unpacking and rebuilding files after SABnzbd finishes downloading the pieces), my playing video goes black, sound stops and several seconds later (maybe 15-30) it just loads up the next file in the playlist and plays it, like it's just given up on trying to get the rest of the file, so it moves on to the next.
I just figured it was my network problem, so I didn't report it, but it sounds very similar to this issue.
Can you tell/find out if the machine serving the video is getting bogged down with something else? I think that's what caused my issue, but i've only seen it happen 2-3 times in the last week or 2, and haven't spent any effort trying to test/identify the cause yet.
In my case, I'm connecting to the library directly (not as a client), but the library is hosted on the server, if that matters.
