I have no experience using them across an entire company, let alone team. So far, it always seemed good enough to keep just each project in a repo. But yeah, for larger projects consisting out of multiple applications, I would not want to work without a monorepo for that.

Many of the benefits from the video still apply, mainly the consistency in code changes was always useful. You can check out any commit and you've got the exact state how everything worked together at the time. No wrangling different versions, no inconsistencies between APIs.
In our build process, we include the Git commit into the applications to have it logged on start-up, so when we get an error report+logs, we can always easily look at the respective code.

But it does depend on your build tooling, if this works well. JVM languages with e.g. Gradle's multi-project builds are great. Rust's workspaces are a treat. Python is fucking atrocious with everything we've tried (pipenv, poetry, lots of custom scripts+symlinks).