I have MPEG Streamclip 1.9.2 and it will NOT recognize MTS or M2TS files. My MacPro with Dual-Core Intel Xeon thinks an M2TS file is a Unix Exe file! Changing it to a MTS only provides all the same errors listed in the previous responses.
FCP — Cannot import or L & T
ISkysoft — can’t de-interlace, poor quality
MPEG SC — Does not recognize file type. How are you bringing the file(s) into the program? Are you pulling a different file out of the folder structure? Or just the xxxx.MTS file?
These files are out of a Canon HF20 and I have no access to the camera or Vixia software (which I would avoid anyway for this terrible compression tactics).
This is all consumer level garbage at this point.