Sony HDR-XR260VE - downloading to a portable hard disc

I have at last found out what is happening.

If the videos are recorded in say HD format but the camera is later changed to SD format the HD videos do not display on the playback screen. It is necessary to change the format back to HD to be able to see and play the HD videos. In the Copy/Edit function after selecting Copy the screens asks which device to copy to. I selected External HDD. The screen then asks what is to be copied ie HD videos, SD Videos etc. Only those videos in the format selected will be displayed thumbnails). The videos are actually in the Stream folder the other folders contain info which launches the Sony PlayMemories software on the PC when the external HDD is connected to the PC. Note also that if the external HDD is still connected when the playback button is selected there will be two copies of the video thumbnail displayed. One is from the external HDD and the other is from the camera HDD. There is no indication which thumbnail is which (other than by playing them - if its the one on the external HDD the light will flicker on the external HDD as it normally does) so it is important to disconnect the external HDD before deleting any of the videos on the camera HDD.

This will be last word on this issue