I don't do much with video, when I do I use Shotcut. I don't understand why drag and drop wouldn't work without a codec. I can understand not being able to view them, but drag and drop shouldn't be affected. 

Thanks for your help. I had tried this way as well with no luck, but I have got somewhere since writing this post. I installed new codecs to my laptop and can now transfer them and view them on VLC player but they will not import into photos app or iMovie.  Can I ask what you use for movie editing? (I had always been able to transfer movies via the Creator App prior to this full day of recording video and then could edit in iMovie. Cannot understand what has changed.)  

Thanks also did this and it did not help- the sensor in the lens had to be at minimum cleaned but i replaced it while i was in there.