Interesting... Did you try opening the preview and downloading it via that? Sounds like that might be an issue with larger files.

You should see the small status bar thingy. I might rework the UI to use the add-on popup one day, because the current one is buggy. Try again once that happens. (not sure when)

The recorder is still experimental tech from Mozilla, and constantly evolving. The UI is a bit difficult to keep consistent on all websites, since they all have their quirks.

If people would leave information like which websites they meet these difficulties on, so I could troubleshoot, then that would be helpful.

Some info on how it's not working would help improve this addon in the long run.