I watch this with my daughter. I only know how to cook because of Alton Brown, so it is nice that my 5-year-old can join me in watching it. In fact, I let her start watching when she was 3. Certainly there is reference to alcohol, in recipes, and occasionally in actual mixology. However, this doesn't bother my family, since we just explain that alcohol is for adults only. For recipes that include it, it leads to a great discussion of volatile chemicals.
AB is an imaginative, funny, and inventive teacher, passionate about what he does, and he doesn't fear math, chemistry, engineering, nutrition, or history. Or beets. Kids can understand some of it, and my daughter knows what an emulsifier is, what happens when you whip cream, and how a lever works, from watching that show.
So unless your family is stricter than mine about alcohol, or doesn't care for occasional dark humor (like the Sweeney Todd Halloween episode, which was so funny I couldn't breathe), I don't see too many potential problems.