[Editor's Note: This answer comes courtesy of John Robison, one of our slot experts who, coincidentally enough, is the author of our book The Slot Expert's Guide to Playing the Slots.]
The class of a machine really has nothing to do with its long-term payback. Class II machines can be very generous and Class III machines can make Scrooge look like a spendthrift. The class, as defined in the Indian Gaming Regulatory Act, just describes how the results on a machine are determined.
Class III machines have Random Number Generators in the software or hardware running the machines. Class III machines determine their results independently.
Class II machines, on the other hand, do not have internal Random Number Generators. They depend on an external system to determine their results. In your example from Wisconsin, the external system conducts a bingo drawing and sends the numbers drawn down to each machine being played. Each machine then looks at the pattern covered by the numbers drawn and makes the appropriate payout if the pattern is a winning one.
A machine's class is irrelevant for reel machines. A 93% payback reel machine pays back 93% in the long run whether it's RNG- or bingo-based.
Class II video poker machines, though, are completely different from Class III video poker machines. Class II machines do not simulate dealing from a fair deck. You can't tell the long-term payback of a Class II video poker machine from its paytable. Strategy is useless on a Class II video poker machine, because your result is determined by drawing bingo balls, not cards from a fair deck.
As you stated, when you play a Class II video poker machine, you're not playing video poker. You're playing bingo.
