The video content you are trying to view may be a low resolution file. To watch a high definition video, the video must have an equivalent resolution or higher than the supported resolution of the TV.
The Internet speed may affect the quality of the video. Check the recommended Internet speed for high image quality with your Internet service provider.
NOTE: Please check the resolution of the video content by using a PC application, such as Windows Media Player.
You can also check the resolution of MP4 content on a Windows PC by selecting Properties from the context menu.