original video is longer than the imported version in premiere pro

[Robert28495597j2sr]

I've been trying to import some videos into premiere pro. The first one is 51 minutes long. As soon as I'm importing it into my premiere project the video's just 34 minutes long. The video drops a huge amount of frames every 6 seconds and the audio stops playing after 34 minutes (but without any other problems). 

[R Neil Haugen]

What is the format/codec of that? And what captured it, screen-grab or camera or ... what?

Neil