We need more information - do you have QuickTime installed? If not try installing this first and the re-import the video.
If this does not fix the issue come back with more information on your computer specification and a MediaInfo analysis of the video file you are importing - see this topic for details and what is required.
...and showing one red mark in top of the file ...
If you are referring to the small red square on the file name in the Media Pool, it indicates that that file is in use in the project. Good if you have many photos in a folder but are only using a few in the project; you can instantly see if you have already used the image in the project.