It is correct that the bigger part of the AfD voters was protesting (not revolting) against something. I will talk about this first and then look at what they are protesting against second.
Tthe 'protesting' part:
When the two biggest german public TV broadcasters were doing the interviews for their election forecasts they questioned people who were coming out of the voting booths. Those people were asked not only which party they had voted for but also for their reasons.
One of the questions was whether they voted for a party because they agreed with its program or rather because they were disappointed with all the other parties.
It turned out that for all parties except the AfD the majority of their respective voters had voted for them because they agreed with their programs.
The AfD on the other hand was the only party of which a majority of their voters (actually 70%) said they had voted for it not because of their program but rather because they were disappointed with all other parties.
So this makes it clear most of the AfD voters really voted for them out of protest.
What were they protesting against is not quite as easy to find out. Mostly because I either have not seen or don't remember an opinion survey about that. I tried to find one right now but didn't.
However: This is the first time I hear its the global elites. I think this is a misinterpretation. In my perception the problem is much more homegrown than that:
The AfD was created by intellectuals (professors and leading corporatists) who disagreed with Germany's adopting the Euro. Then when the Greece financial crisis hit, the party opposed the perceived (from their perspective) bailout of Greece by Europe in general and Germany in particular.
They did
not really have a program beyond these issues.
The party did have some sort of nationalist tendency insofar as it did not want Germany to support other Euro countries but it was not a Nazi party.
The party changed when the refugee crisis hit:
While an astonishingly big part of german society supported and still supports an open-door policy many people see the practical difficulties this brings and have their doubts. And another part of the poplulation - a not so small minority - strictly opposes the influx of refugees.
The AfD immediately adopted this topic and indeed became the
only party actively opposing the government's refugee policy. Their former topics (Euro/Greece) have taken so much of a backseat by now that hardly anyone remembers that 'oh right, that's what they want too'.
The last federal elections were 2013. That was before the refugee crisis. At that point the AfD was still a mostly intellectual anti-Euro-party and stood at 4.7% of the vote which meant it did not clear the 5% - hurdle and thus did not make it into the Bundestag.
Then the refugee crisis hit, the party adopted that topic and now they are at 12.6% of the vote.
I think it is very clear that the majority of their voters sees the influx of refugees as either their most important topic or at the very least one of the most important topics.
That means - to me - that the AfD voters are really not protesting some 'global elite' but rather have a very concrete problem with a certain german policy position by the german government and a big part of german society.
Now not in reply to you, biochem but rather in reply to that article you cited: The article complains that some members of the AfD are being called Nazis.
Well:
Every new right-wing party in Germany since WWWII has always had the same problem: that immediately when a new right-wing party forms and seemingly has some success every Nazi-nut (and there still are some out there) jumps the bandwaggon and tries to take it over.
This is what happened to the AfD too.
And there unfortunately are enough of those nuts left that the people who have originally founded the party have left it disgusted and one says about it: 'We spawned a monster.'
Here some quotes by the AfD leadership:
The party leader said that refugees trying to illegally cross the border should be shot. (That is the same AfD leader who now walked out on the party on the day after the elections because she is too
moderate for the direction the party is taking. No joke.)
When her deputy was asked to clarify whether that means she thinks that women and children who try to enter the country through some open meadow should be shot at she replied with 'yes'.
Their leader in the state of Thuringia said he does not just want Germany to have a 1000-year old history but a 1000-year future. (I suppose you know that Hitler kept talking about a 1000-year 'Reich' so that number is no coincidence).
The AfD leader of the state of Niedersachsen claimed that most of the 'so called arson attacks' on refugee shelters were committed by the refugees themselves.
One of their leaders in the state of Baden-Württemberg called president Obama a 'quota-nigger'.
The Vice-chief of the federal AfD denies that climate change is being caused by humans.
That same guy said that Germans should be proud of the achievements of their soldiers in WWI and WWII.
The AfD leader of the state of Saxony-Anhalt said 'how sick in gender and spirit, how unnaturally degenerate is this red-green following (red-green following meaning the voters of the Social Democratic Party and the Greens).
If those guys aren't Nazis then I don't know who is.
It is however also true, that most of their voters do not agree with their program (what there is of that which isn't much aside from anti-refugee). So yeah, not all of their voters are Nazis. But the party leadership has more than their fair share of them.