Download mockup without background - Photoshop

Hi!

I was wandering if there is a possibilty to download a mockup without the background. 

I already designed the mockup without the background, but if i render the video and download it after, the background appears in black. I would like to make it a MP4-file.

Is there any way to make it dissapear?

I'm working in Photoshop 24.7.