PowerPoint 2010 is very similar to its predecessor, except in the way that it works with movie/video files. It has always been the case with PowerPoint that movies are not part of the presentation file, but are kept separate. A presentation would consist of the PowerPoint file, ppt/pptx and the movie files, e.g. wmv/avi/mpg. In PowerPoint 2010 the default action is for movies to be embedded into the PowerPoint presentation, there will no longer be a separate movie file.
A movie embedded in a PowerPoint 2010 presentation by default will not work in PowerPoint 2003 or earlier, and will only work on some versions of 2007 depending on Office service pack. However there is an option to overide the default action and save the file separately. On the Insert tab select Video >from file. Browse to the file you wish to use, and select it. In the bottom right hand corner of the Insert Video window, from the drop down menu Insert, select Link to File. The movie will now be saved separately, and (Subject to PowerPoint /movie compatibility) will work in earlier versions as well as 2010.
If however you are going to stay with PowerPoint 2010 be sure also to "Optimize compatibility" in this way movies such as QuickTime will (at last) play within in PowerPoint. So if you decide to insert a QuickTime (MOV) for example, insert the movie so that it is embedded (i.e the default action, not linked. ). Then click on the file tab and select Info and click on "Optimize Media Compatibility". If an appropriate format, the movie will be optimized, and with any luck, Your QuickTime movie will now play.