We've usually produced Mpeg1 files for sending out video clips to corporate clients (they play them on their PC's and Macs) - basically cos it's been the most widely acceptable format without any loading of specific sofware (as PC's have Media Player and Macs have QuickTime, both of which will play Mpeg1).
However we've had problems recently encoding Mpeg1 on OSX and I've still to find a decent reliable encoder. But maybe times have moved on and we should leave Mpeg1 behind.
Is Mpeg4 the way to go now.... which version of this would play across a range of PC's and Macs???
TIA
Steve