Hello Lynne,
Thanks for reaching out!
You can check out this article to see all of the available options for adding videos to your Storyline 360 course:
If hosting your videos in a public hosting site is not an option for you, the next best thing that we can recommend is to lower the resolution of your videos instead. You'll notice that there is a significant difference in file size between a 1080p HD video, and a 720p video. If you're interested in going this route, you can check out Handbrake which is a free tool that you can use to lower the resolution of your videos.