Ok Video peeps here is whats going on,

I have tested recording a video mix by using quicktime to record the screen on the macbook, so im recording the serato video screen. Then i'm recording the sound output via the mixer into my imac and using ableton.
It all worked ok, the video quality wasnt mega amazing but was decent enough, my idea was that i would put both sources together in adobe premiere pro.
My problem is something seems to have happened with the video, as when i came to put it together its out of sync. I have spent some time trying to match the sound up to the video and no matter what happens if its correct at the start of the video then it is out of sync at the end ( 3 track period approx 5mins) and if i do it opposite then its out of sync at the start? Correcting the sound delay on the video so it syncs up shouldnt be an issue as i can correct this in the post edit???
Project setup perhaps in premiere? different frame rates playing it back different perhaps?
Render the video in premiere as well to make sure nothing strange was happening.

any thoughts people?
and also any suggestions on better ways at recording everything, using latest versions of serato and video serato.