Yes, you can make a copy of the profiles you are currently using and create a new GUID at the top of each file as this is how Mezzmo uniquely identifies each profile. Turn on transcoding and try playing some files, if you find a file that you think should be played without transcoding you can delete the transcoded file from the properties of the file in Mezzmo on the Transcoding tab then select to Use Original file and see if it plays. If it does then you can get ffmpeg information of the file from the right click menu and look for the container name in the profile. then add the codec for video and audio if it is not already there or adjust the properties of the codecs if they are already there to include the file.