''video starts here'' comments??

can anyone tell me what these comments mean lol i only see them under their videos

https://preview.redd.it/pw892lqxypjg1.png?width=888&format=png&auto=webp&s=372d3faf22d268d493fc11953aef517175b51336

https://preview.redd.it/b5fpnlqxypjg1.png?width=534&format=png&auto=webp&s=bb51721705b1960ba25d7f675d0ee3cf3a9f317e

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