Best way to share a screencast to these forums?

I am working through the Practical Machine Learning for Coders Part one and have a question about the material. The best way to explain it would be to show a screencast of me running the notebook. Does this site allow attaching mp4 files to the posts and is there a file size limit? If not, anyone have a suggestion about where to post such a file?

Plan B would be to turn the video into an animated GIF and post that, but I would like to keep the audio track if possible, which I can’t do with a GIF file.