This is already on my to-do list. Unfortunately, the alternative APIs (DirectShow et al.) have their own issues and dependencies and are more complicated to use. As the MCI method is used throughout mIRC and has been tweaked over many years to work the way it does across different versions of Windows, it would take much work, several version releases, and a lot of user testing on any new method before it will work in a way that is hopefully reliable and backward-compatible.
