Right, instead of even, odd, even, odd… the consoles do even, even, even, even… (or odd, odd, odd, odd… as the case may be). Same number of fields per second, just half the resolution at double the framerate.
Re: the softfilters, they’re CPU-based filters rather than GPU-based. They’re a bit limited at the moment insofar as they only work with certain pixel formats (though the new API allows for different formats), but yeah, blargg’s SNES NTSC is in there (also works for NES, except for a single-pixel problem with the way it samples above the top line, IIRC), though some people reported crashing with it. The feature obviously isn’t 100% yet, but it’s primarily there for platforms that can’t expect a programmable GPU pipeline.