Video&Ad is stuttering with ProtectedMode enabled

Hello Adobe Team,

this Video&Ad (Audio is ok) is stuttering for me with ProtectedMode enabled:

http://www.myspass.de/myspass/shows/tvshows/tv-total/TV-total-Sendung-vom-04032013--/11937/

(I hope it will be playable outside germany)

If I disable ProtectedMode, then it is ok.

MainPC:

ASUS M4N82 Deluxe; AMD Phenom 1090T BE; 2x 2GB EX2-4800P2-SX DDR2-800-CL5; Gigabyte GTX 650 Ti OC; Samsung HD103SJ,  SyncMaster 204BM und 225BW

nVidia Driver: 314.22

Tested with:

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0 // 20130408165307

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:23.0) Gecko/20130413 Firefox/23.0 // 20130413030927

Hardware acceleration = enabled (disabled not tested yet)