ok, since the url generated for the logo is for example
http://static-cdn.jtvnw.net/jtv_user_pictures/forsenlol-profile_image-48b43e1e4f54b5c8-300x300.png
It looks to be constructed from the user username and some guid part. I thought that guid part could be constant (ex. the guid of the user), so even if the logo changes, the url would stay the same…
I am still unsure