[gars]

WMP just isn't a very good media player - especially when playing high bitrate files or custom codecs. You're lucky that it's just a second delay when you're seeking. If you have a crappier computer, it might actually mean the video playback will be choppy. You can try installing k-lite packs - like c_loke suggested.... but not sure if that will solve the problem.

but honestly, I just stick with VLC for my video playback - there's so much more it can do.