I've got a Kindle Fire HD 7".
With "software decoding" enabled :
There is a green bottom line on the videos. The buttons aren't transparent (black background).
The thumbnails in the library are affected too.
With "hardware decoding" enabled :
Playing videos is fine now.
But I rebuild the library and re-generate the thumbnails : the green bottom line is still on the thumbnails.
I use the latest nightlies (I can tell that all the ones builded this summer are affected).
I can provide logcat of a special step if it helps.
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Not related : there is a French typo in the preferences menu.
<string name="directories_summary">Sélectionnez les repertoires de votre bilbiothèque multimédia</string>