Full DirectShow support so filters like
Haali's Media Splitter and
VSFilter can be used, as they are usable in all other sane DShow players. Not trying to heckle, I would really like to see this done. I am sure it is quite possible because at one point in time in the past, these two filters were easily used in BSP. However since more "advanced" features were added it broke any compatibility with them, and likely many other powerful DShow filters as well.