Making “fly-throughs” or tours in Google Earth is relatively straightforward. You don’t need a paid version of the program and yet the results can be brilliant. Here is an example of a tour from the source of the Nile to the mouth.
In order to play the tour, simply click on the unzipped folder (not the contents or the original zip file) when it appears in the Places window, and then click the play arrow as shown on the screenshot below:
The method is fairly straightforward, simply create placemarks of the desired tour locations and save them in a new folder. Re-arrange the placemarks in the order they should appear before playing the tour.
With a long tour like my Nile example it might be necessary to preview the individual placemarks to cache them locally so that the presentation plays smoothly.
The method is described in much greater detail at Google Touring. You can share your tour on this site too.
Thanks to Rob Chambers for his original query!