Replying to Got me a mac and now i need some help

alright so i have been a longtime PC user and recently made the switch to the dark side... with that im wanting to change up my workflow a touch. ive been looking at different options to transcode my .MTS files to prores and have had some shitty luck... Ive been told MPEG streamclip is the shit but im unsure on how to make that work as its telling me I need the MPEG2 quicktime bullshit. now im on the newest version of OSX and i shouldnt need that plugin as its already installed? Any advice for a mac noob who needs to get his shit together for clients?