I had to disagree with Rod's take on it, and after I'd posted the comment, I realized that I'd said pretty much what I would say about it here. So, aside from one brief mention of the person to whom I was responding over there, here's what I said, and what I think of the whole thing:
First things first: Catholics (and Orthodox) consider marriage a sacrament; that is, marriage, the natural state, was raised by Christ to the level of a sacrament, an outward sign instituted by Christ to confer grace. So any Catholic person (or, presumably, Orthodox) who wanted to create a display like this at his wedding would be quickly told "no."
Now, from my understanding this couple is Lutheran; it is my further understanding that Lutherans do not consider marriage a sacrament, though it is a "covenant." So I wouldn't hold Lutherans to the same in-church conduct as I would people of my own faith--yet, sadly, many young Catholics are more influenced by this sort of thing than they ought to be, and become downright horrible when planning weddings (e.g., what do you *mean* I can't have this or that pop tune for my wedding march? etc.).
So, on what grounds other than general grinchiness can I possibly object to this spontaneous display of joy? Several:
--it's clearly *not* spontaneous, but planned and staged, and thus has all the appropriateness of a couple's deciding to re-enact Juliette's balcony scene in the midst of exchanging their vows,
--it's extremely self-centered of the wedding party, in that they aren't thinking at all about the sensibilities or comfort of their invited guests who may *not* appreciate the beat and lyrics of the song playing or the gyrations of the dance,
--it's turning the already inappropriate "Bridezilla/Bride as Oscar-night Red Carpet Starlet" motif of most modern weddings into a "Bride: the Musical" iteration that we will probably all grow to hate in a few years, as imitators and wanna-be YouTube stars try to outdo this particular gimmick,
--it reinforces one of the most terrible notions of the modern wedding, the idea that it is the "bride's day," (with occasional nods toward the groom who isn't wholly forgotten) and that she gets to have Whatever.She.Wants. Including choreography sessions with her bridesmaids, who are not chosen for the honor of it but because they will wear whatever hideous get-up the bride picks (including sunglasses) and do whatever she wants them to do, including practice a "dance entry" designed to take YouTube by storm.
In other words, somewhere we lost the notion that a wedding was a day of celebration involving families and communities, in which cherished family members and dear friends would be invited to witness the solemn and decorous exchange of vows signaling a couple's intention to remain together for life and to aspire toward becoming a family (e.g. having children) themselves, and re-invented the wedding as a spectacle with ever-increasing entertainment value but little to no value in terms of a lifelong commitment or a desire for children, neither of which is even remotely implied by most modern weddings. Guests are expected to attend these "command performances" and supply lavish gifts of money or consumer goods in exchange for their "tickets" and the dinner/dance which follows, but their comfort and their sensibilities are the last things on anybody's mind--which, since the guest list often drops extended family in place of the bride's hundred or so closest gal pals and their dates, isn't entirely unforeseen.
In a word, it's pretty selfish for a bride to subject her guests to a startling and vulgar display of any sort--but the problem is that we've created and embraced a cultural myth which declares that a bride is *supposed* to be selfish--it's her one day to act like a spoiled child and get away with it, and who would deny anybody such a harmless pleasure? (Except a grinch like me, naturally.) :)
Since people who read this blog aren't, thankfully, shocked by Catholic notions, I'll only add that in some ways, it's a real problem that marriage isn't considered a sacrament by other churches (again, except for the Orthodox, though I believe for them a marriage after divorce is not considered sacramental, though it is permitted). But in all honesty I see this "wedding dance" as being a problem of etiquette--one simply does not subject one's guests to such a vulgar display during the ceremony on purpose, and doing so is extremely rude, no matter how happy or joyful one wants one's celebration to be.
Besides, as I said above, this whole thing wasn't even remotely spontaneous--and joy is not something that is planned and staged by a bridal party with one person (likely the bride, though not necessarily) counting down and snapping her fingers "Four, three, two, one, and go, and go, and...people, people! We've only got until tomorrow to get this right!"