Why can't the video sync with the audio

[AC Question]

i downloaded a video (mkv format) and the video won't sync up with the audio. At first it syncs, but then it would gradually not.

 

[Laura Knotek]

What device do you have, and what version of Android is it running?

What app are you using to play your video?

Is your video stored in device storage or on an SD card? If it's on an SD card, what are the specs of the card (what class)?