I am running Yosemite 10.10.4 and just ran up MIRawViewer V1.4.3 and loaded a raw video. Was able to view and export (as a MOV).
So it looks as if it is not a general ops system issue. Would suggest you delate the MIRViewer version you have a re-download in case there is a corruption.
So it looks as if it is not a general ops system issue. Would suggest you delate the MIRViewer version you have a re-download in case there is a corruption.