Since Word documents are one of your bigger concerns, you can download LibreOffice on one of your current machines and try them out. That’s the same program you’d be using on Linux.
It’d have to be a pretty unusual video format to have issues. Similar to above, you can try VLC on Windows and see if there’s any issues.
Based on your description, I’d be surprised if you encountered any major issues. I’d recommend trying either Pop! OS if you’re OK with a slightly different UI from Windows, or Mint if you want something more comfortable. Note that you can create a LiveUSB stick of either of those, or any other distro. You can then boot your computer from it and take it for a spin to see if there’s any obvious issues.