So far in this guide you have learned how video poker started and grew. You have learned the basics of video poker play including return, house edge, and variance. You have learned about how randomness actually works while playing at the casino. You now know how to determine your bankroll size. You may even know what specific video poker game (or games) you want to play. If you do not, you have some idea how different video poker games behave and their major characteristics.
Once I hit two 4 of a Kinds back to back.  The probability of hitting it once is 0.24%.  The chances of hitting it back to back are 0.24%2 = 0.0006%, or 1 in 179,000.  That's four times less likely than hitting a royal flush.  And I would have preferred the royal!  (By the way, purists will note that after you've hit a 4 of a Kind, the chances of hitting another four of a kind is just 0.24%, not 0.0006%, but I'm considering the probability of getting two back-to-back before I get the first one.)
You learned in chapter 3.5 that progressive video poker has one (the royal flush) or more (other high paying hands such as a four of a kind) jackpots that increase as the game is played. You also learned that as the progressive jackpot increases, the strategy to play video poker changes so that more of the close decisions are decided in favor of saving for the higher paying and less frequent jackpot hand rather than some more frequent but lower paying hands.
A straight is a hand with consecutive ranks, like 9? 7? 10? 8? 6?.  Notice again that the cards don't have to appear in order.  The order of face cards, from lowest to highest, is Jack, Queen, King, Ace, which we abbreviate J, Q, K, A.  An ace can also count as 1, to complete a straight where the other cards are 2, 3, 4, and 5.  But it can't count as both a low and a high card, e.g., Q K A 2 3.