Help? How do you safely convert from HD .m2ts to .avi?

[HelpLuperza]

Right now I am helping to work on designing astronomy lab for local college. The lab will measure the declination of the sun using time-lapsed photograph (see picture), similar to what I did in my undergraduate years.

When I orginally did this lab back 2009, the video camera I was able to take .mp4s turn them into .avi's so I could make time-lapsed pictures using virtual dub and gliffy. However, the file formats have changed since now alot of video cameras record in HD.

This new "fancy" video camera uses .m2st and .mst, which are video format I have never dealt with before. I would really like to design this lab with the same methodology (the same steps) that I used in 2009 so I would like to get the video's in .avi

Does anyone know an free/inexpensive and mostly lossless way to take a .m2st file and make it .avi or .mp4?

[Hamma]

Check out http://handbrake.fr/ it will probably do it.