Sometimes , I best remember a performance seen on video or TV screen due to a mere gesture, sound, outfit, opening trick, that is -made to help emphasizing the special essence of that performance.
Charles Aznavour's performance of his famous song "Hier Encore", will always be remembered by me for the singer's...moans; yes, moans.
Aznavour was accompanied by two young, beautiful female singers. Whenever it was the turn of each one of them to sing, he raised his eyes up to the young girl, and...moaned. The moans were to express suffering and pain at his lost youth (the subject of his song).
The above are only two examples; there are some more in the mentioned category.