A few thoughts...
I think it is fair to say that normally we think about cutting a 2-space jump with the high move at 1 below rather than 'a' as played. Did you consider this and reject it, or not really think about it?
- Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X . . . . . . . . . . . |
$$ | . . . . . . . 1 . . O . . . . . . . . |
$$ | . . . O . . . a . , O X X . . X . . . |
$$ | . . . . . O . X . . O X . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
I would like to suggest that 50 (below) was a worse move than 20!

The play at 20 stemmed from a reading error. Although Shenoute is right that connecting under would have been much better, we've all panicked from time to time when we've made a mistake. However, 50 betrayed a very poor assessment of the overall situation. This is harder to fix than ladder reading.
First we should realize that the marked White stones are strong. They form a good, solid shape. In addition, Black's small group on the left is not completely alive so it is difficult to imagine that the White stones will be cut off (OK, this actually requires a careful assessment of the life and death situation on the left but no way should White be imagining that the marked stones are in danger). So the question arises how should White use those stones?
Another feature of this position is that fundamentally White can invade a large knight shimari like that in the upper left and live. If you check Sensei's Library, you can find info on that shape and related invasions.
So White needs to think about how to continue. Two things that White should not want to do: protect strong stones that do not need protection and prompt Black to protect the upper left shimari. White 50 manages to do both.

The exchange up to 54 makes Black's corner safe and White's left side over-concentrated.
To my eye White probably wants to calmly enclose the upper right at 'a' instead of 50. It is the biggest point left IMHO (bigger in fact than either of the connections at 58 and 62 played in the game

).
- Click Here To Show Diagram Code
[go]$$Wcm50
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . a . . . . . |
$$ | . . X 4 . . . . . , . . . . . O . . . |
$$ | . . 2 1 . . . . . . . . . . . . . . . |
$$ | . . 3 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . W W W . . . . . , . . . . . , O . . |
$$ | . X X W . . . . . . . . . . . . . . . |
$$ | . . X X W . . . . . . . . . . . . . . |
$$ | X . . . . . O . . . O . . . . . . . . |
$$ | . X X X . . O X . . . . . . . . . . . |
$$ | . X O X . . O X . . O . . . . . . . . |
$$ | . O O O . O X X X , O X X . . X . . . |
$$ | . . . . . O O X . . O X . . . . . . . |
$$ | . . . . . . O O X X X . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Of course 66 should have been in the other direction at R16.
At 76, just connect solidly. The marked stone below protects the cut at 'a' and means that Black can not resist here... Black will have to live in the corner and White will get to attack the two Black stones to the left anyway. There is a connection at 'b' remaining for White.
- Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . 3 . |
$$ | . . . . . . . . . . . . . b . 1 O X . |
$$ | . . . . . X . . . . . O . X . O X 4 . |
$$ | . . X X . . . . . , . . . . . O X . 5 |
$$ | . . X O . . . . . . . . . X . . O X 9 |
$$ | . . O O . . . . . . . . . . 2 . O X . |
$$ | . . . . . . . . . . . . . . . . O 6 8 |
$$ | . O . . . . . . . . . . . . . . a 7 . |
$$ | O . . . . . . . . . . . . . . . . . . |
$$ | X O O O . . . . . , . . . . . , W . . |
$$ | X X X O . . . . . . . . . . . . . . . |
$$ | . . X X O . . . . . . . . . . . . . . |
$$ | X . . . . . O . . . O . . . . . . . . |
$$ | . X X X . . O X . . . . . . . . . . . |
$$ | X X O X . . O X . . O . . . . . . . . |
$$ | X O O O . O X X X , O X X . . X . . . |
$$ | O O . . . O O X . . O X . . . . . . . |
$$ | . . . . . . O O X X X . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Whether White could have captured Black after White 90 is beside the point. White did a very nice job of building territory while attacking Black through 156. White added territory at the top, in the center, and on the right, playing in a very consistent fashion. Having a nice feeling for this is more valuable than being a little better at finding a killing play.
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Dave Sigaty"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21