QUES: In open rhinoplasty make a small incision in the skin that separates the nostrils band

correct the punctuation.

CORRECTED: In open rhinoplasty, make a small incision in the skin that separates the nostrils band.

QUES: But the thing is that a single correct definition does not exist

correct the punctuation.

CORRECTED: But the thing is that a single correct definition does not exist.

QUES: We need to make sure DVD Shrink will not change the quality of our video Transcoding is the last step remember So we need to click on the automatic option in the video pane and change it into No compression

correct the punctuation.

CORRECTED:
We need to make sure DVD Shrink will not change the quality of our video (Transcoding is the last step, remember?) So we need to click on the "automatic" option in the video pane and change it into "No compression"