403: Invalid response for http://www.youtube.com/oembed?format=json&maxwidth=620&maxheight=300&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DEYbvhWEG6kE
[math]\left(a\pm b\right)^2=a^2\pm2ab+b^2[/math] und [math]\left(a+b\right)\cdot\left(a-b\right)=a^2-b^2[/math]