I started to used a McBook air because my laptop wasnt working properly once I starded to edit the clips. Using the same videos on my Mac many of the vids wont play, in can see the clip on the import box. Once the Vid is the I move the courser over it will turned green, you hit play and the vid will be all jumbollup. I used the Zhiyum and Film Mic pro app.
Please let us know if you were able to solve the issue you were facing with preview.