I would start by looking at your cellular contract. Many have daily or monthly limits of data limits unless you have the means to jump to 3G from LTE you may end up not being able to watch a full TV or movie presentation. If that is the case see if you can watch the TV show or movie connected to WiFi, does that work?
Next I would see if the phone its self is getting warm. If it gets too hot it can shutdown fully until the temperature drops. If that is the case try placing the tablet on a cooling pad to help dissipate the heat.
You may need to ship it to the closest Samsung repair depot your self to get it fixed.