There is two possible issues here:
The first is the reliability of the connection to the source. This could be the server offering the stream all the way to your system via all the networks it crosses. The data stream breaks down enough the video part is unable to recover. If you back wind the vid to a section that was good it should recover.
The other possibility is the player is unable to buffer enough of the stream. This gets into how much RAM you have and available drive storage and if the connections data rate is very low it too can effect things. Ideally, you want to buffer in RAM, but if your lean on RAM as other apps are using it your drive will be used. If the data rate is low you may need to allow your system to buffer the vid before playing it.