Files are from a Canon T2i, and play fine in LR 5.7 64 bit. Turned off video acceleration, which fixed the develop module problem but not video playback. I can mouse over and see movement in the library grid view, but when I double click one clip to open loupe, it opens with no playback controls and crashes LR after a few seconds. I applied the latest update. No help.
I have the same problem. Windows 8.1 x64 Pro with plenty of horsepower and disk space. This was not an issue with LR5. The files were created with a Nikon D7100, so I don't think the type of camera is the issue. I have included the error from system logs. ATI Radeon HD 2900 XT Video card with latest drivers approved by Microsoft. I know it's an older card, but should handle this with ease.
Faulting application name: lightroom.exe, version: 126.96.36.199, time stamp: 0x553af4c6
Faulting module name: unknown, version: 0.0.0.0, time stamp: 0x00000000
Exception code: 0xc0000005
Fault offset: 0x0000000000000000
Faulting process id: 0x2e4
Faulting application start time: 0x01d09f341c09a72d
Faulting application path: C:\Program Files\Adobe\Adobe Lightroom\lightroom.exe
Faulting module path: unknown
Report Id: 6b0fd99c-0b27-11e5-8362-10c37b9c1f99
Faulting package full name:
Faulting package-relative application ID: