I can find the ID twice. Here is an example:
www.google.de/maps/place/Magdeburg/@52.1285424,11.6312738,3a,75y,98h,90t/data=!3m8!1e1!3m6!1s _k_6ZCbrOuYAAAQo8TPM1w ! 2e0! 3e2! 6s% 2F% 2Fgeo3.ggpht.com% 2Fcbk% 3Fpanoid% 3D _k_6ZCbrOuYAAAQo8TPM1w % 26output% 3Dthumbnail% 26cb_client% 3Dmaps_sv.tactile.gps% 26thumb% 3D2% 26w% 3D203% 2695% 3D28% 3D953% 98fwa 7i13312 8i6656 4m2 3M1 1s0x47a5f5ff55daea5b: !!!!!! 0x4236659f8071060 6m1 1e1
I got the url by clicking hte yellow guy (in the lower right bottom corner) and clicking one of the orange spots of the panorama
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