I've captured a vhs tapevideo h.264 in mp4 holder. Used Elgato capture card. Captured video plays beautifully until edited.

[netjockey]

Loosing sound synch when editing.

 

[Tcinator]

Its gotta be the framerate in the timeline your working in.... find out what the framerate on your capture is and match that to the project and make sure the samplerate of the audio matches too.. if you are still having issues, what are you editing with program wise?