Can you tell me what this zsh function does and what the parameters mean?

```zsh
video_trim() { ffmpeg -i $1 -ss $2 -t $3 -vcodec copy -acodec copy $4 }
```
Sure. The zsh function you provided, `video_trim`, takes four parameters:

* `1`: The path to the input video file.
* `2`: The start time of the trim in seconds.
* `3`: The duration of the trim in seconds.
* `4`: The path to the output video file.

The function uses the `ffmpeg` command to trim the input video file and save the output to the specified path. The `-ss` option specifies the start time of the trim, the `-t` option specifies the duration of the trim, and the `-vcodec copy` and `-acodec copy` options specify that the video and audio codecs of the output file should be the same as the input file.

For example, to trim the first 10 seconds of the video file `input.mp4` and save the output to the file `output.mp4`, you would use the following command:

```zsh
video_trim input.mp4 0 10 output.mp4
```

I hope this helps! Let me know if you have any other questions.
Thanks!