Question:    All five cards are on the board, 4 diamonds (the Ace,7,8,2), and one club, the 8.  Both players have the flush, one with the 10, and one with the King with the cards in their hands. Who wins?

Some are saying that the King high wins, but others are saying that with the Ace on the board the flush is just high and it's a split pot.

Answer:    In Texas Hold’em, it is not unusual for players to have hands that are closely valued on showdown.  The rules of poker apply to Texas Hold’em and the rank of the cards in each flush must be counted carefully to determine a winner.

In the example you presented, the two flushes are compared as if they were no pair hands.  The highest ranking card on the board is the same for both players, being the Ace of Diamonds.  As such, the next second-highest ranking card is compared.

The player with the A-K-8-7-2 flush would win over the other player with the A-10-8-7-2 flush.