MPG is a Common video format standardized by the Moving Picture Experts Group (MPEG); typically incorporates MPEG-1 or MPEG-2 audio and video compression; often used for creating downloadable movies.
Wondershare Video Converter Pro for Mac is an amazing Mac DVD Ripper and Video Converter all-in-one . It also can convert FLV to other popular video file formats such as AVI, MPEG, WMV, MOV, VOB, etc. With it you can even convert AVI, MPEG, WMV, AAC, 3GP, etc. video to FLV video.
Free download and install MPG to QuickTime Converter for Mac
Step 1, Load video files to Mac MPG to QuickTime Converter
Click the "Load" button to add video files to the Mac video converter pro.
Step 2, Set output format and output folder.
Choose the file you want to convert, click "Format" drop-down button to choose MPG as your output format, then click "Browse" button to choose destination folder for saving your converted AAC files. This Mac Video Converter Pro also can convert FLV video to all popular formats on Mac for iPod, iPhone, PSP, PS3, Mobile Phone, Apple TV, Zune, Creative Zen, AAC players and MP3 players and so on.

Step 3, Change video and audio Settings
You can change the Resolution, Encoder, Bit rate and Frame rate of the video and Sample Rate, Channels, Encoder and Bit Rate of the Audio. The size of the file depends a lot on these settings.

Step 4, Start Conversion
When you get ready to convert the added videos on Video Converter Pro for Mac, click the Convert button to start conversion and then you can just go out for a walk or take a nap, and the conversion may have been finished when you come back.
