Youtube has started to artificially slow down video load times if you use Firefox. Spoofing Chrome magically makes this problem go away.
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Posted in r/youtube by u/vk6_ • 9,648 points and 935 comments

Aqui estão comentários explicando o script intencional usado pelo YouTube para prejudicar o Firefox: https://www.reddit.com/r/firefox/comments/17ywbjj/comment/k9w3ei4