Just happen to have some video footage in AVCHD format? That would be "Advanced Video Coding High Definition"—you know—HD video files. If you've got some of those MTS files (like from a Canon HG10 camcorder) you want to open in a program that doesn't support them, like QuickTime or Premiere Pro, then you're going to have to convert them to a different format. Here's a way to convert them without losing the quality. You'll be converting the MTS files into HD WMVs at 4,000 kbps with a program called TMPGEnc 4.0 Xpress and Premiere Pro. You can also set as H.264 at 4,000 kbps.