To fix this, if on 3G, connect to Wi-Fi, or move to area with stronger signal.
TVPlayer uses what is known as multi-bitrate streaming, meaning that each video stream has multiple different qualities within it.
The streams contain a Low (L), Medium (M) and High (H) quality variants.
This means that if you watch BoxNation and have a slow or weak connection, you will likely be using the Low quality stream, but if your signal improves, the stream will automatically increase the quality upwards on its own, you don't need to reconnect. This is also the same if you are moving from a good quality signal to a slower one, the stream will adjust on its own.