1. Insert audio files
    You can easily insert an audio file into PowerPoint by clicking “insert -> movie and sound -> sound from file”. This allows you to link an external audio file inside a slide. Thus when transferring slides to another computer, you need to copy the audio file as well keeping at the same location with the slides.In order to embed an audio file within a slide, you need to do two things:
    a) click “tools -> options -> general tab”, change the “link sounds with file size greater than xxx kb” and make it bigger (maximum 50M);
    b) convert the audio file into .wav format. You will get a huge file, however, you still can use Microsoft compressed wav file format to get a fairly small wav file. Then embed it into your slides. Done!
  2. Insert video files
    Remember, video files cannot be embedded, but always linked.
    PowerPoint can only handle avi/mpeg/wmv/asf files as Windows Media Player can handle. If you want to insert a video file from YouTube(http://www.youtube.com), You need to follow the following steps:
    a) download the .flv file from YouTube by using online downloader website: www.youtubex.com;
    b) convert .flv file to .avi/.mpeg/.asf by using SUPER (http://www.erightsoft.com/SUPER.html#Dnload). I suggest you convert it to .mpg (MPEG-I) or .asf formats, because the converted video can be easily inserted into PowerPoint. Avi format is a bit tricky since it uses MPEG-4 codec. Powerpoint cannot play it if the codec is absent, and you cannot guarantee another computer will have the codec installed.
    c) if converting .flv to .swf (still using SUPER), you need to insert an shockwave flash object from the control toolbox toolbar. Then you can specify the path of the .swf file in the properties dialog box, and change “EmbedMovie” to “true” if you want the flash movie embedded.