Webm files don't work by default with git LFS

[mansona]

Describe the bug

I enabled LFS for my repo and for some reason most of my files were working, but the webm files just didn't work

To Reproduce

1. Fork the repository at https://github.com/mansona/emberconf-lint-to-the-future
2. Create a Netlify site and link it to the forked repository
3. Make sure to enable LFS by setting the GIT_LFS_ENABLED environment variable to true
4. The Netlify build succeeds but when you navigate to a slide with a webm file it just doesn't load

Expected behavior

I expect the webm files to behave like all other files covered by LFS and be downloaded effectively by default

Additional context

I am already opening a PR to solve this issue but there is more discussion around this topic on this thread https://answers.netlify.com/t/webm-not-working-under-git-hub-lfs/14460/4