Did a bit more investigation after watching back some of my MTB videos from the weekend and as I suspect there is definately a sync issue on some of the imported videos/GPX tracks.
I was recording trails at approx. 5 mins a time. Looking back some are spot on, 1 is about 5 seconds out and another about 15 seconds!! Now the Virb did hang with red light stuck on and had to power off - but after that all seemed ok.
So if the VIRB Elite is writing both the mp4 video and GPX files why would they not be in sync? I know I can adjust the sync in VIRB Edit, but if I was going to do that I should have saved my money and bought the Normal VIRB and imported my Edge 510 GPX files.
Is this a camera recording issue or a VIRB Edit problem?