Can't see Thumbnail or open MPEG-2 videos with QT

Hello, I am new to MAC and not really a computer expert. I have transfered all my video mpg2 files on my new MAC (from a Sony DCR-SR85 which has a hard drive / i transfered the file to my computer as if it was an external drive). Thumbnails do not appear and i can't open with QT (no codec). I can open with VLC, but to check the file, rotate them, etc... i would like to see the thumbnails (so no need to open them 1 by 1). I looked at a few forums and responses seem very technical so i could not figure out what to do; i still have checked that:

- I have OS 10.7.5 so reading MPG-2 should be possible ?

- i have found in system / library / QT file (after struggling to find how to get there...) that i have indeed a file Apple MPG2 Codec component

- i have also read it might be the Sony files are not exactly MPEG2 ?

My main aim is to locate the Video which need to rotated, so i can do the same with Image Browser from my Canon Camera.

Is there is an easy fix, that would be great. I there is a specific Software which could help, i may get it.

Thanks for your help.

As it is the first time i try to post sth on internet, i am not even sure how i will see respone if any, but that will be the second step.

😕

Cheers

Serge