Hendrick's horse tea?

Has anyone ever tried this with your horses? Would it be a good way to entice a horse to drink, especially in winter? Thoughts?

Here is the link to the video of how to make Hendrick's horse tea
Recipe For Hendricks' Horse Tea - Video Dailymotion

I've heard of similar things being done, but I've never tried it (I've never had a horse that wouldn't drink, they've all been very good about that). Seems like an interesting idea.