I believe that in this case it is an affectation for the purposes of the video, c.f this live performance , where standard modern technique is used.
Basically, I think that some combination of the artist and the director thought that it would look more archaic.
There are indications that earlier Baroque technique would involve holding the instrument lower .
And of course, the viol de gamba would be played with the instrument in the lap.
Overall, I find this posture most similar to how the nykelharpa is held;
which is a significantly different instrument in that mechanical keys are used to stop the strings.
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I've seen folk fiddlers hold the instrument like this - on the breast rather than under the chin.
I agree, holding THAT low is probably artistic licence.
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In Jean Roch Coignet, there is a fiddler playing "Fanchon" on violin.
That's how I first saw this stance.
He holds and plays it from the hip.
It's near the end of episode 3.
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I can't imagine there is any justifiable advantage to playing fiddle like this.
I'm not a fiddle player, but it seems like the left hand might have it's work cut out for itself, having to hold the instrument in a playable position while moving up and down the neck to land on the notes with any kind of precision.
It reminds me of the old expression, sawing on the fiddle.
I expect it would feel very much like trying to play guitar without a strap while standing, definitely not easy to do.
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It would make singing at the same time easier.
Lower positions (usually it would more be ribs than hip) are sometimes seen in folk styles.
I think I've seen it "in the wild" in Budapest with a restaurant fiddler.
Stefan Skrzypek 's style, in comparison, is rather idiosyncratic.
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I cannot seem to find a reference to this practice anywhere outside of this video     (seen from the beginning (~0:32) of the video) Is there an official term for this type of stance? Are there any advantages or disadvantages to playing like this? Or, does it violate some kind of general violin posture rules?
Holding a violin against the hips?
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<technique><strings><violin><styles><posture>
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I'm not a violin player, but it seems like the left hand might have it's work cut out for itself.  Lower positions (usually it would more be ribs than hip) are sometimes seen in folk styles.   Lower positions (usually it would more be ribs than hip) are usually seen in folk styles.  
it seems like the left hand might have it's work cut out for itself.  Lower positions (usually it would more be ribs than hip) are sometimes seen in folk styles.  