I reread the answer as I was copying it and you do have to move in a straight line, but you can do it in any direction that is in your front arc.
Shadow4ce, no he did not say within or totally with in. Below is the response.
Rule Question: Do walker move in a straight line from their front arc. or can they move any direction in their front arc? (Example diagonally)
Walkers can move in a straight line in any direction so long as their line of movement falls into their front arc. In this sense, a walker is capable of diagonal movement. However, the walker's facing at the end of its movement must remain the same as it was at the beginning of its movement. A walker can rotate up to 90 degrees before or after moving, but no rotation can occur during the move itself.
I hope this has answered your question. Happy Gaming!
Zach Tewalthomas Assoc. Miniatures Games Producer Fantasy Flight Games email@example.com