Video problems
 

I have had a few situations lately when downloading some videos. Some videos are for example 10 minutes but when I view them only the first 40-50 seconds are viewed and then it stops and for the next few seconds you only hear audio from the rest of the video and then it completely stops. Now if I move it back and forward you are able to see pieces of the rest of the video, is this compression problem/mistake, can it be fixed?

Try another player like Mplayer .
This is due probably to a corruption that must have occured during the download process: missing or corrupted data that prompt your current player to stop reading the video data at the point of the corruption but to keep reading the (uncorrupted or whole) audio data.