Video with transparent background in Storyline 360

Sure, I first simply grabbed a stock video from the service our organization subscribes to (in our case iStock). This was to be the animating background seen on every page of the 84-slide project. I then placed the video in the Master slide on the root level so every page would open with the video playing on it. This is the bluish background with the animating lines seen on the sample slide I shared.       

Now for the tricky part.     

On some individual slides, I knew I wanted additional videos to play on top of the animated background. Hence the transparent video in Storyline dilemma. After finding an appropriate stock video for any given slide in the show, I created a 'composite video' using Adobe After Effects where the base layer is the same animating video used on every page, and the one time use video is feathered with a mask in AE and placed over the base. I timed it properly to fit my needs and saved the composited video.

Then in the Master Slide area I created a sub-master screen that used the newly created video only once. Then in storyline I simply called for that slide to use that sub master slide as its input. Since the base video was the same as all the other slides it matched perfectly with all other slides in the show.

I only used the effect for a few slides because of the costs of the subscription videos. Also, it would be a very large file to have too many different sub-master slides being called out for every page.

You could use your own created videos from a phone or any source to avoid using subscription videos. Also, any software that can create a composited video would work to accomplish the same effect. I happen to know After Effects enough to accomplish the needed task. It is not hard to learn AE enough to do this.

Hope this helps. If I can be of further assistance let me know.  -joe