Transparent Background on videos

Hi all,

I am in the middle of making some improvement to a previous course and I am encountering some issues with some videos that have transparent backgrounds.

Essentially, on the existing course the videos have transparent backgrounds but when imported back into the new course they turn black.

I found this link : https://community.articulate.com/discussions/articulate-storyline/movie-transparent-alpha-channel

but as its a little old it does not answer my specific question which is....

We want to go away from using Flash but would like to continue to utilise the video content with some minor tweaks to the start and finish.  Are transparent backgrounds supported in Storyline 360 without the need for Flash?

If so, is there any free software that would allow me to take the existing video content, make minor amendments and then export it in X format so that it will display correctly?  Ideally we want the video to be compatible for all browsers including HTML5.

Thanks all