Split Video From Command Line Using FFmpeg

I was writing a post about You Dont Mess With Zohan movie and I had to split a 50 second video from it.

I have Vlc installed, so I enabled to view the advanced controls and recorded the required portion.

Once it is done, I played it back,  but the audio and video are not syncing. I tried again and the same thing happened again.

This is the video splitted with Vlc.

Next, I splitted video with ffmpeg using this command.
ffmpeg -i input.mp4 -vcodec copy -acodec copy -ss 01:20:12 -t 00:50:00 out.mp4
I splitted correctly and audio/video are synced perfectly well. 

This video is split with ffmpeg.