MPEG with multiple resolutions/videos in it

[wtfhits]

This isn't actually a VLC question. The reason I'm asking here is because VLC is the only player that works at all for these types of files, so I figure someone might know why.

I have a few files which apparently have multiple videos in them.

VLC can play them fine - and at one point it just switches between the two. The resolution changes, and the name of the file flashes up again - as though it's treating it as an entirely new file.

But nothing else can handle this. They just see the first one and either completely ignore the second, or fail to load the video. Some do succeed in continuing to load the audio though.

When I use MediaInfo, it says it's an MPEG-PS container, and only informs me about the first video (in the duration and width/height fields for example).

My first thought was that the file simply contained multiple program streams, but my (brief) research indicates that's not possible.

So my questions are:
how would this be possible?
is there a way of analysing/splitting these videos (for free ideally!)?