the problem is with audio - there is never an exact match between the audio and the video frame rates-

so you have to do the next best thing -which is different for every scenario-

with audio playback-
if you have a single layer - and you need it to look perfect -you have to set playback to the highest setting supported by the display-
screen 1 div 1 -

this renders everything at 60Hz- or 75Hz- and gives a chance to the video frame rate to reach the screen