You should have a dedicated internet connection of minimum 5 Mbps to ensure good quality streaming. Please In order to verify this, check your internet speed at http://www.speedtest.net/
If you are using a wireless connection, you should try connecting via LAN. The wireless signal can be weaker than the LAN, causing interference with the broadcast and lowering the picture quality.
If you are watching on your PC, you should choose the Quality setting applicable to your internet connection speed. If your internet speed is lower than 768 Kbps, you should use the low quality option. If it is higher, then use the high quality.