Open the Tour editor and see if the video is displaying there
If not, make sure that the order details is has the display slide show selected to display in Tour Media
If it is selected to display, see below
If the format of the tour is Story, then the MP4 file has not been completed. The MP4 file is not created until after the tour has been published. Check the Video Generation queue and if the file has not been started enter it as a priority. The MP4 file is not created until after the tour has been published.
If the format is Full Page or Web page 2.0 - This is an issue with the Adobe Flash program on your computer. Please see the article concerning Flash. Or wait until the MP4 file has been created.