Concatenate clips with as little code as possible in AviSynth+
function SegmentedDissolve(string base, int first_val, int last_val, string format, int dissolve_length ){
    filename = base + string(first_val, format) + &quot;.MOV&quot;
    result = FFMS2(filename)
    return (first_val &lt; last_val) \
        ? Dissolve(result, SegmentedDissolve(base, first_val+1, last_val, format, dissolve_length), dissolve_length) \
        : result
}

SegmentedDissolve(&quot;F:\_DSC&quot;, 1, 9, &quot;%03.0f&quot;, 50).Trim(3600, yyy).FadeIn(100).FadeOut(100)

You would need to figure out what value yyy needs to be for the concatenated clip. If the first clip needs to be trimmed on both sides, then the first clip should not be included in the function (start first_val at 2), and instead get loaded, processed, and concatenated manually.
As a note, the FFMS2 function also loads up any audio found in the specified clip, so you do not need to dub it unless you are doing processing on it first.