Argue pointlessly with Al about history and so on

[The Mikado]

Why was the German working class so pro-Nazi?

Pre- or post-the Nazi takeover in 1933?

[The Mikado]

How frequent were Medieval peasant uprisings?

Totally depends on the part of the Medieval period you're looking at.  You want massive, frequent, important peasant uprisings?  Look at the 14th century.

I'll let Al weigh in, of course, as this is his thread, but the 14th century is a fascinating period of near-apocalyptic upheaval from famine, revolt, war, and, of course, the Black Death that conspired to rip the social order of the Late Middle Ages to shreds.

EDIT: a few of the more famous ones:

http://en.wikipedia.org/wiki/Peasant_revolt_in_Flanders_1323%E2%80%9328

Covered nearly all of Flanders (northern half of modern Belgium) between 1323-1328, forced the Count of Flanders to flee into exile, and had to be put down years later in a full military campaign.

http://en.wikipedia.org/wiki/Shepherds%27_Crusade_(1320)

Mob intended to form a crusade against Iberian Muslims, when Philip the Fair (Philippe IV) refused to pay them they went on a rampage and burned down much of Aquitaine before they crossed the border into Aragon and were crushed.

http://en.wikipedia.org/wiki/Peasants%27_Revolt

The great English Peasant Revolt of 1381, an incredibly famous event in English history.

[The Mikado]

Why did the ruling elite in Britain allow democracy to prevail?

You skipped this one. Its very broad and (delliberately) a bit naively phrased, but its good for internet bickering, so why not have a go at it?

By the time what Al considers democracy prevailed, Britain had just exited a catastrophic World War and was facing a full-fledged rebellion in Ireland and the elites were in no position to "disallow" anything.