This ad is apparently controversial. I'll let you figure out why because I couldn't.
Assuming you're talking about the coke ad (youtube links don't work in my browser at work), it's controversial because it was frankly a hamfisted display of every progressive cultural idea you could jam into 60 seconds of airtime. I guess my issue with it (and I remember noticing it at the time, but had honestly forgotten about it until now) was that it was just too overdone. You want society to be accepting and diverse, then show normal amounts of diversity every day in normal every day things. Making a grand and obvious show of it smacks of white folks constantly making a point of talking about their black friends.
It's trying too hard IMO. You defeat the entire point of the exercise if you're beating people over the head with your image of a perfect multicultural world. More problematic is that you more or less do it intentionally to invite backlash. There's a point where it's not really about someone being bigoted but rather just being annoyed that you're constantly putting "let's all not be bigoted" messages in front of them. It's insulting really. Kinda like how if someone stands in front of you and says "Let's not fight" over and over for an hour, it's going to really make you want to hit that person in the face.
And frankly, since I noticed a number of comments in response to Leahy's response, there's a difference between people of multiple cultures and backgrounds becoming one America (which is the idea behind the whole "E Pluribus Unum" angle) and people of multiple cultures and backgrounds demanding that America must adjust to them instead of the other way around. Totally different. So yeah, having people singing America the Beautiful in multiple languages does kinda send the wrong message. Actually, not "kinda", it does send the message that a beautiful America is one where everyone speaks all these different languages. Which is certainly controversial.