Open Script in the script editor and select "Open URL" Script Step.
At the bottom right there is an option "Perform without dialogue". Make sure it is checked and you will not see the dialogue. I am attaching modified file
Sorry, looked it up in the FIleMaker 13. If you are using 15, right click on the Open URL line or click on a cog icon to see the same option.
music.fmp12_NK.zip 195.7 K