You are right. I left that out of the video to focus on the more interesting features. There is a small note on the website about how text selection could work with gaze and touch:
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Text Selection
Place one finger on the touchpad to adjust a cursor at the gaze position. Use a second finger to set the end of the selection.
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Text Selection
Place one finger on the touchpad to adjust a cursor at the gaze position. Use a second finger to set the end of the selection.