I will do this at some point when I have time,
It sounds like a reasonable suggestion that the runtime actually reflects the version you have since there are many reasons why the IMDB runtime could be out eg NTSC/PAL, directors cut etc.
I'll try to do it for the next build, although this will be limited to those who have media details enabled in the preferences.
If I forget then remind me, sometimes people ask me to do fairly simple things and because they are simple I leave them until last, by which time I have forgot all about them.