Vinegar is an acid, when you ingest it it makes the blood more acidic and therefore thinner and easier to push through your veins. I have no idea how exactly. I'm not sure if aspirin (which is an acid) works in the same way either, but that thins the blood too.
You're supposed to take it to counteract the hypertension caused by too much protein ingestion, but only about 2 teaspoons of it in a glass of water, not drink the shit straight.
No not an aphrodisiac, but its a practice in India called amorelia. Its when they drink urine in the morning to help bring about relaxation and meditation. LOL Im not joking.
Never heard of the vinegar thing thinning the blood. I assume that the naturals buffers in the blood would handle and it, especially in the stomach. The whole pH thing is not very nice in there. And some people who dont produce enough stomach acid take vinegar to prevent stomach upset, sort-of a reverse heartburn/tums deal. Apirin or acetylsalycilic acid making blood cells "slippery" preventing coagulation is done by a different protein process.
And Ive heard of some college football teams giving pickle juice to players who cramp up. They swear by it, but I dont know about the hard evidence, might just be a very sour sugar pill.
Of course, Im mainly talking about like white vinegar at a reasonable amounts, if there is another compound at work, then who knows. MY two cents and I crave vinegar in foods some times even straight, so Ive pondered this before.