New to my X-T3 and videos won't move correctly to macbook

[Claudine]

I am not a professional and have very little experience, so please respond to me like I am an idiot, but when I try to watch videos on my macbook that I moved from my camera, they act like they're playing, but the screen is either black or frozen. I have been connecting my camera to my macbook with the power cord and photos and videos automatically open up in my macbook camera roll. They then go to the cloud and can be accessed on i-phone as well.... except when I open the longer videos to watch them, there's nothing to see. I move the videos into I-Movie and it just shows a black screen. I have deleted all the videos from my camera already, so the only thing I have is what's on my macbook. Have I lost these videos for ever or is there some way to salvage them?  And.... in the future, how do I get photos and videos off my camera and on to my macbook without this issue happening again? My firmware is updated now for both the camera and the lens. I also just bought an SD card reader. Am I supposed to move the photos from the SD card to the macbook with the SD card reader rather than using the white power cord to connect them both? Thanks for any and all advice.  

[Greybeard]

The best way to move movies is to use a card reader. There is a limit to the size of file (4GB) that can be moved via cable - you don't say how long those videos are but it could well be the reason you are having problems.

[Claudine]

They differ... at first, I thought it was the videos over 15 min or so, but today I noticed a few around 4-5 min were not working either. 

[Greybeard]

1 hour ago, Claudine said:

They differ... at first, I thought it was the videos over 15 min or so, but today I noticed a few around 4-5 min were not working either. 

Check the size of the file - even 4-5 minutes can be over 4GB which is the limit using the cable