>That is up to whoever called AddSubtitleFile.

It's OpenInputStream() in that case. I'll move it there.
I should comment my commits more verbosely ;)
If a user sets subtitles on per default, plays a video without subtitles and stops playback stream=-1 and subs off are stored in the db. If he manually adds an external subtitle file to the video's folder, the subtitle will not be auto selected.

I'm willing to admit that this is really a special case ;)