Videos from Dropbox to PC can't be played?

I have videos stored in my Dropbox and can't play them on my PC. Neither with the "App" on the laptop, nor via Internet Explorer o. Chrome. The audio works, only there's no picture. Anyone ideas how can I get the videos on my laptop with audio and picture?

Poor computer performance can impact streaming. Can be so difficult to answer exactly what it is

The VLC player can play almost everything and it will be easier if the video file is stored on the PC.