Using ffmpeg to convert one file to another remains probably my main use of general LLM web searches. This isn't to say it does a good job with that, but it's still ahead of me.
Just like with regexes I've yet to get a wrong result by doing "give me an ffmpeg command that does this and this" with an LLM, with Handbrake I'm never quite sure what I'm doing, too many checkboxes and dropdowns with default values already filled in.