Real vanilla extracts are between 30-70% alcohol. I'm not sure about Watkins specifically.
well, it's not commonly accepted that vanilla alone gets you high, it may not, and probably doesn't.
But there are a load of chemicals in vanilla, and there are neuroreceptors in the brain which correspond with vanilloids, and seem to be related to pain response, capsaicin (chile peppers) may be related to vanilloid agonist. Cannabis may also have some affect on vanilloids.
Bear in mind, however, that raw vanilla also contains a number of really nasty potential and known carcinogenic aromatic penoles and benzene compounds and only a minority may (and likely aren't) psychoactive. It's fine by 1/8 teaspoon in your egg nog, but probably not so healthy by the half pint. So drinking a bottle of vanilla might get you drunk, but it might also damage your liver in the process, and not even get you high.