you say your using shadow play to record your screen in games?
i know when using FRAPs a long time ago, i would drag the video into vegas and it would be RED - so corrupt - some parts of the other videos i draged in would play at some point, but RED at other points.
This can be due to a RAID configuration problem when mirroring the file, or can be due to a problem that's much alike going into i|Tunes, clicking on a song only to find out it cannot be located - because you've moved the song files somewhere iTunes cannot find it.
''i know this is'nt a solution, but it gives you and idea of what might be happening!''
as for ShadowPlay i have no experience with, so try downloading FRAPs for free as a trial, and draging video recorded from that as a 3rd solution, to see if it's something your doing wrong when recording with ShadownPlay, or if it's just that ShadowPlay is the problem.
GoodLuck!