Due to the way videos are stored in our backend, it's not possible to download videos that you've uploaded to Xperiencify. (It's because we cut the video up into chunks, in order to optimize playback speed).
So, we highly recommend keeping local backups of all of your files as a best practice.
But, if you DO need to download videos, you may be able to do this with a tool or plugin designed specifically for this.
One that you can check out is Downie, a tool for downloading videos from the internet.