I have just converted to Apple and face a compatibility problem: When trying to transfer mpg videos from my digital camera (Samsung) i first had to download a piece of software (mp2 something). Now the transfer works but there's no sound.
Generally speaking, "muxed" MPG (i.e., MPEG-1) files are "playback only" compatible with QT. This means you should be able to offload files directly to computer and, assuming there are no timecode break/unterminated file container problems, should play back as they are. They would not, however, be "edit" or "conversion" compatible with QT applications. For instance, they would not import into iMovie for editing and/or QT 7 Pro/QT X would only convert the video content without audio.
Now, as to whatever it is you downloaded, if you are referring to the QT MPEG-2 Playback component, that is used for the viewing of video content encoded as MPEG-2 and does not play a part here unless the content is actually encoded as MPEG-2. In either case, "muxed" content (other than MPEG-2/AC3 camcorder content imported by video editor apps) is not converted to frame-level video compression formats with a separately synchronized independent audio track by the QT Player (7 or X).
In the above cases, the normal approach is to use a third-party application like MPEG Streamclup (free) to bridge the gap between files containing blocks of audio and video content interspersed in a single data stream to QT content which has independent audio and video track content synchronized at the frame level. This work flow should work for either "muxed" MPG (MPEG-1), MPEG (MPEG-2) files. (NOET: QT MPEG-2 Playback Component required for MPEG-2 content.)
One additional complication. Recent users, primarily those with the QT MPEG-2 Playback component installed when upgrading to Snow Leopard) have reported losing their audio playback in MPEG2/MP2 files. This is a separate issue and may or may not have anything to do with your problem. In some cases, re-installing or updating the MPEG-2 component has fixed the problem while for others it has not.
I suppose there's a difference between mpg and mp2
On a Mac, MPG normally refers to a multiplexed MPEG-1 file. However, this extension is frequently used as a generic indicator for MPEG-1 or MPEG-2 content by PC/Windows users. MP2 refers to audio content -- specifically MPEG-1, layer-2.
