A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
I have an idea that might help. First, a look inside PPT's head.
PPT will only play animations (e.g. your auto-start video) when you've moved TO the slide containing the animation FROM a prior slide.
You can trick it by adding a "dummy" slide just prior to the slide with the animation. If you set the slide to transition automatically to the next slide after zero seconds, it'll happen so quickly that the dummy slide won't even have time to appear. If it does blink on, you can always use a copy of the slide with the animations (ie, your video) as the dummy slide (but remove any animations).
To get this to work you might also have to make a custom show of each dummy slide + video slide pair. Then instead of linking to either of the slides, link to the custom show and choose to show and return.
That way, clicking the link will show the video then return to the slide with the video "postage stamps" ... from there, the switch can move to the next postage stamp slide, as you're already doing.
Whew! Complicated!