Video clips will play better with faster Internet connections. Users with a high-speed connection (DSL or cable) should experience high-quality video. Users may experience longer loading times while using cellular hotspots and lower bitrate download speeds while the video buffers before playing, and users may experience buffering as the video plays.
For best results, It is always recommended to be hardwired to your internet provider. WiFi presents so many more issues and problems that are almost impossible to track down.
If you are on a wireless connection try switching to a wired connection, or move closer to the wireless router for a stronger signal. Also, if you are running other bandwidth intensive programs you may want to quit out of these as they could be taking away from your available bandwidth.
One way to check your wireless connection is connect your mobile device to cellular data and see if the stuttering improves. If the stuttering improves, it is likely your wifi router should be rebooted.