I bought an IMac awhile back and just got around to trying to play videos recorded on my Sony handy cam that is about four years old.   The videos are .MPG format but will not play on quick time.  They used to play fine on my old HP laptop.  Any suggestions for the computer illiterate.

Edit: Upgraded to Mountain Lion and now everything works fine.

here you go


Brian

Try Perian codecs or VLC media player.

Edited above.  I see Perian is being shut down.