I only have PhotoStory 2013. I don't know what you mean by "PC slide show" and I don't see this under Export. If you are just trying to show a slideshow somehow on your computer without creating an export file, then it probably will not pick up the videos, only the photos. Remember that PhotoStory does not import your images, it only uses them to create a file. It does not modify the source files. When you "Export" or "Burn" you are creating a video type file that is created by PhotoStory using your images, videos and audio. Thus if you want a slideshow file that you can show on your computer or on someone else's computer, you have to export it and use the resulting file. You do not need to put it on DVD to do this, simply use "Export" and "Output as a video file" and select the file type and quality that you want. Or go to File - Export and you have a selection of file types. PC slide show is not one of the options.
I cannot find the "Burn to PC." When I click on Burn, I get the screen to create a disk menu. When I click on the second Burn button, here is the screen that I get:
Logically, I can't see how one could burn to a Slideshow to PC or Online Album. They have to be export files.
Be careful with both as they can either just be the images themselves and the PC or the Online Album has to be set up to run the slideshow. Or and as I do, create a video file wmv, mpg or mp4 and use it for both cases.
If you are doing a lot with both photos and videos, you would be best off with Movie Edit Pro. It may be time to upgrade the next time you get a good offer from them. Go for at least the Plus version.