I see dead balls
I don't agree with the assigned probabilities or even to assign probabilities at all to a real life situation with too many unknown factors. I'd say the exact probabilities are unknown. However, I do know there are many reasons for someone fainting (medical), without taking any drugs or alcohol. You can faint from just standing up too quickly. All manner of medical problems, low blood sugar, low blood pressure, dehydration, overheating, allergies, seizures, sleep deprivation, exhaustion, fever....I believe if you had to assign numbers to such a situation, you'd at least have to adjust your probabilities very heavily towards "natural" causes. I've seen people black out from all of the above. We can probably rule out external trauma before the fall, but that of course is one reason to faint as well.33%--This is the chance that this has a medical explanation of some kind that does not involve drugs outside of alcohol, and alcohol may have been a marginal or major contributor.
33%--The chances that this is due to a drug/s, whether legal or illegal, that she intentionally took but is trying to hide that and keep it secret and not admit to it for whatever her reasons.
33%--The chances that this is due to drugs, legal (prescription or over the counter) or illegal, that she does or would fully admit to taking but as of yet just doesn't realize are what caused the problem.
1%--The chances that somebody spiked her drink or she got jarred, and the chances actually went down to about .1% after the video was reviewed showing that nobody messed with her drink but I'm calling it 1% just to have a nice round number.
All sorts of things can lead to a "shock" reaction that can dilate your blood vessels suddenly, causing you to faint. Once a girl I brought to a restaurant fainted from smelling a spicy dish..It was a fancy restaurant and they brought her back with smelling salts. In medic training, one candidate had to be dropped because he consistently fainted at the sight of blood, lol. I mean, talk about choosing the wrong path..Another fainted from needles, dropped out as well.
Alcohol of course is a possibility. Sometimes, when you've been fasting, if you're slightly ill etc alcohol can really sneak up on you in unexpected ways. It also tends to amplify any other problem one may have, so the intake can be very moderate and have a very powerful effect. I'm not a doctor, I've just seen this happen a few times. A girl I know drank while sick and taking antibiotics...bad idea. Blacked out and had all sorts of problems after only 2 drinks. People are idiots sometimes.
Recrational drugs exist, may be a cause, but are socially stigmatized so lets not speculate on that. Don't know the woman, have no idea if that is something that she'd ever do and won't speculate.
I do agree that the drink spiking seems a bit far fetched, though not impossible. The syringe theory may also be possible. I'm leaning towards natural causes, from the little information we have. And really, people should get the benefit of the doubt until we know more.