Just would of been to tell her. Your pretty safe suggesting .mp4, avi and mkv's.That info should be available in your TV's user manual.
I would say consulting the manual is far more savvy than posting a question online..If someone is savvy enough to post a query on a forum and know about different file types I assume they’re also able to search for specs and user manuals.
In the “olden” days before the internet if you wanted to know how to do something with your TV you consulted the user manual…that's still the case.