I uploaded a similar video earlier but I had a discussion with my student last night about not getting bogged down in Chi Sao.  Chi Sao is not fighting.  It's a tool to help compliment and facilitate your fighting applications.  

Master and Apprentice: Master Victor Parlati and Sifu Ki Innis

A very light and friendly spar with my sifu, Master Victor Parlati.  Trust me, he was REALLY being soft with me basically just keeping me in check.   Light as it was, it was a good exercise in the principles of keeping the line.