Add support for alternative xvideos urls.

[Stephan972]

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Description of your pull request and other information

ytdl doesn't recognize xvideos urls like the one below :
https://fr.xvideos.com/video13287221/
Did you notice the 'fr' subdomain before 'xvideos.com' domain ?

This patch addresses this issue and other alternative valid xvideos urls rejected by youtube-dl.
xvideos2.com, xvideos.es, it.xvideos.com, de.xvideos.com.