Will a German blu ray disc work on a US format?

It is unlikely that US material will work on European equipment for two reasons. First, North America operates on a 60Hz field rate, meaning that images are delivered to the screen 60 times each second. In Europe, the field rate is 50Hz. Color encoding is also different for analog signals. Many European players and monitors will adjust automatically if they see 60Hz content so this problem is not seen often with modern equipment. The second problem is a bigger one. Commercial DVDs and Bluray discs are region coded. A disc that is coded for North America will only work on North American players. Likewise, European discs are restricted to European players. Some DVD and Bluray players are region free, meaning they will play any disc from any region. These tend to be professional decks rather than domestic. Also, non commercial discs do not have the region coding and can also be played on any disc. The only way to be sure is to try it and see if your set up works. If it does, then it is a bonus for you.