What are the PC's specs: CPU/GPU/RAM?
Two missing files... 
But the 24-minute available content is synchronized, both in preview and H265 export at 1080 mp4, using this Videopad release.
Confirm that the PC's video driver and Direct-X are current.
AMD / ATI users: [http://support.amd.com/us/gpudownload/Pages/index.aspx](http://support.amd.com/us/gpudownload/Pages/index.aspx) Intel users: [https://downloadcenter.intel.com/default.aspx](https://downloadcenter.intel.com/default.aspx) nVidia users: [http://www.nvidia.com/Download/index.aspx?lang=en-us](http://www.nvidia.com/Download/index.aspx?lang=en-us) Update DirectX: [http://support.microsoft.com/kb/179113](http://support.microsoft.com/kb/179113)