AVCHD video clip format
MTS is a file extension for an AVCHD (Advanced Video Coding High Definition) video clip format for high-definition video.
The MTS file format supports 1080i (a high definition video format with 1080 horizontal scan lines, interlaced) and 720p (720 horizontal scan lines, progressive scan, rather than interlaced) in a relatively small file size.
AVCHD video files can be burned to Blu-ray discs and played in compatible devices. Sony and some Panasonic video cameras have software to open and edit MTS files. Other players convert the files. AVCHD files are based on the MPEG 4 codec.
Programs that can open MTS files include Roxio Popcorn and Creator, Flash CS5, and various Cyberlink players.
Learn more about MTS files:
The AVCHD site explains AVCHD Video Clip - MPEG Transport Stream.
See questions and answers about video displays on ITKnowledge.com.
Wikipedia has an entry about AVCHD.
The Microsoft Developer Network has directions for How to Convert MTS to any format.