Human Friendly Filename Detection
Javascript, 466 bytes

s=&gt;(s=s.split(/\.[a-z\d]{1,6}$/i)[j=d=0],h=s[l='length']/2|0,m=[],g=r=&gt;(++j,m=m.concat((s[n='match'](r)||[]).map(x=&gt;[x,j]))),p='replace',g(/\d{9,}/g),g(/[\da-f]{16,}/ig),g(/[\da-z%+=]{12,}/ig),m.sort((x,y)=&gt;y[0][l]-x[0][l]).every(x=&gt;x[1]-1?x[1]-2?s=s[p](x[0],y=&gt;y[n](/[a-z]/)&amp;&amp;y[n](/\d/)&amp;&amp;(y+'A')[n](/[A-Z]/g)[l]&gt;y[l]/3|0?(d+=y[l],''):y):s=s[p](x[0],y=&gt;!!y[n](/[A-F]/)^!!y[n](/[a-f]/)&amp;&amp;(y+'0')[n](/\d/g)[l]&gt;y[l]/3|0?(d+=y[l],''):y):(s=s[p](z=x[0],''),d+=z[l])),d&lt;=h)


Explaining:



f=s=&gt;(                                 // f: take string s (filename) as input
    s=s.split(/\.[a-z\d]{1,6}$/i)[j=d=0],  // s: input without extension
                                           // d: combined rules' sum
                                           // j: combined rule-number step
    h=s[l='length']/2|0,                   // h: half string
                                           // l: length
    m=[],                                  // m: matches
    g=r=&gt;(++j,                             // j: next combined rule number
        m=m.concat(                            // m: join
            (s[n='match'](r)||[]).map(             // new (r)egex-matches
            x=&gt;[x,j])                              // mapped with its rule number
    )),p='replace',                        // p: replace
    g(/\d{9,}/g),                          // combined rules §1
    g(/[\da-f]{16,}/ig),                   // combined rules §2
    g(/[\da-z%+=]{12,}/ig),                // combined rules $3
    m.sort((x,y)=&gt;y[0][l]-x[0][l])         // matches ordered by length
        .every(x=&gt;x[1]-1?                      // for combined rule §1
            x[1]-2?                                // for combined rule §2
                s=s[p](x[0],y=&gt;                        // for combined rule §3
                    y[n](/[a-z]/)&amp;&amp;y[n](/\d/)&amp;&amp;            // if lower and digit and
                    (y+'A')[n](/[A-Z]/g)[l]&gt;y[l]/3|0?      // upper at least `total/3`
                (d+=y[l],''):y)                        // replace by empty and sum up `d`
            :s=s[p](x[0],y=&gt;                       // replace if
                !!y[n](/[A-F]/)^!!y[n](/[a-f]/)&amp;&amp;      // (upper xor lower case) and
                (y+'0')[n](/\d/g)[l]&gt;y[l]/3|0?         // digits: at least `total/3`
            (d+=y[l],''):y)                        // by empty and sum up `d`
        :(s=s[p](z=x[0],''),d+=z[l]))          // no treatment
    ,d&lt;=h                                  // output if "no more than half of string"
);


["results_for__michael_greer.txt.zip",
"Georg Feuerstein - Connecting the Dots.pdf",
"M People - Search for the Hero-ntuqTuc6HxM.mp4",
"index.html?v=QTR4WGVTUzFsV3d8NHxvcmlnaW5hbHx8MTExMTAxBHxodHRwOi8vLCwsLHRyLDcsMA%3D%3D.html",
"ol2DCE0SIyQC(173).pdf",
"d41d8cd98f00b204e9800998ecf8427e.md5",
"12792331_807918856008495_7076645197310150318_o.jpg"]
.forEach(x=&gt;document.body.innerHTML+='&lt;pre&gt;"'+x+'" =&gt; '+f(x)+'&lt;/pre&gt;')