ffmpeg may let you open the .mts and convert to .dxv - i'm currently exploring this route also for use in resolume. there are GUIs for it but it's essentially a command line interface.
@Vitaliy_Kiselev I already have the VJ software (Resolume + MAX MSP). I am going to shoot lots of short clips to VJ with and I am looking for Mac software with which I can load the clip, trim a selection, then save as 'in the codec that works best with the VJ software (DVX, quicktime)'. Simple + fast without making projects etc.
tsMuxeR is the only tool I know of that can reliably trim .mts files from the GH2 without recompressing them. Even then, I would not trust it completely. Hang on to your original camera files if they are important.
If you are fine to recompress the video in the process, there are hundreds of tools for that - any video editing tool that can read AVCHD.