This is a problem with the person who made the PPT and can affect images,
videos, etc.
In this case the PPT is LINKING to the Quicktime video which doesn't exist on the new computer. Not sure if PPT is capable of embedding a QT video as part of the presentation and keeping it SAVED as part of the presentation/slideshow.
Same thing happens with images. Hi-Res images get downsized many times when saved and ported to another computer.
In all of the cases I've seen it's because the PPT was created on a Macintosh running a Windows VM. Not sure if this is the case here.