Thank You!

I modified my RegEx like so:

            (                   # start of capture group 1
            {{                  # match an opening 
                (?:
                    [^{{}}]++   # one or more, non backtracking
                      |
                    (?1)        # found {{ or }}, so recurse to captur
+e group 1
                )*
            }}                  # match a closing
            )                   # end of capture group 1
[download]

The problem is that this does not match if I have {{ something {{{ text }}} }} in my content ...