On 5d Mark III 1.1.3 latest nightly:
Today I received my new cf card and did an unattended test, I recorded for 10min at 1920*1080@25p with audio (but mic was off) to check the stability of the card. Recording went completely normal, files are ok, playback via MlRawViewer completely normal.
Playback on camera with mlv_play failed while indexing. 10 out of 13 files seem to get indexed, than an error occured repeatedly: Index error mlv_play can be exited normally, there is no index file on the cf. I can't say if it stops always on the same file, but always with the same error message. It says 10 out of 10, but there are 13.