I've just bought a dash cam and wondered whats the best android app for viewing the footage and zooming in?

Unless it comes with special software I guess you'll be stuck viewing them like any other video.

 

I've got a Transcend camera and it comes with it's own app.

If it's a standard sort of camera with no wifi etc to connect to other devices for playback, you can either remove the memory card and put it in your phone to play back (if you have that capability in phone), or if an android phone buy an OTG cable to read the memory card and play it back using an app like 'MX Player'. 

Yes it has wifi and I was after an app to manipulate the vid - zoom in etc