regex – What is the correct syntax of a list involving regular expressions (non-typical usage in a browser extension)?

So, I’m struggling with configuring options in Aria2 Download Manager Integration extension for Firefox. In the ‘Include file type’ field I’m supposed to list a number of file types to be captured by aria2c downloader. There’s a hint below the option text-box suggesting to use ‘Regular Expressions: (that) Matches MIME type’. The extension only picks up one value at a time, e.g. application/octet (for archives and executables) or image/jpeg (for .jpg images). If I use image/*/, PNG-images get included as well – as if the wildcard is somehow recognized! I’ve tried several types of delimiters to keep the file types separate: backslashes, some common html and unix separators. The extension seems to ignore them. What am I missing here? Is the regular expressions syntax just more complicated so that placing correct delimiters in a list is not enough?