The main bulk of this is the new start screen code. To make this work in Raze some more work on the startup procedure is needed.
What this does provide is support for the DOS end-of-game text screens in Duke and SW on non-Windows systems.
These are both lengthy operations that can take several 100s of milliseconds, so when starting a streaming video they can throw off the timing quite significantly.
With this the intermissiondelay counter could be removed as it was only there to flush the accumulated time before starting video playback.