Configured. Redesign a little bit plugin (also added s.getVisitStart function, which is missed in documentation)
/* Plugin: Visit Start */
s.getVisitStart = new Function("c", "var s=this,v=1,t=new Date;t.setTime(t.getTime()+1800000);if(s.c_r(c)){v=0}if(!s.c_w(c,1,t)){s.c_w(c,1,0)}if(!s.c_r(c)){v=0}return v;");
/* Page Visibility Plugin 0.1 (BETA) */
s.getPageVisibility=new Function("",""
+"var s=this;if(s.getVisitStart()){s.Util.cookieWrite('s_pvs','');s.U"
+"til.cookieWrite('s_tps','');}if(s.Util.cookieRead('s_pvs')&&s.pvt<1"
+"){if(parseInt(s.Util.cookieRead('s_pvs'))<=parseInt(s.Util.cookieRe"
+"ad('s_tps'))){s.Util.cookie"
+"Write('s_pvs','');s.Util.cookieWrite('s_tps','');}}s.pvi=setInterval(s.pvx,100"
+"0);s.wpvi=setInterval(s.wpvc,5000);");
s.gbp=new Function("",""
+"if('hidden'in document){return null;}var bp=['moz','ms','o','webkit"
+"'];for(var i=0;i<bp.length;i++){var p=bp[i]+'Hidden';if(p in docume"
+"nt){return bp[i];}}return null;");
s.hp=new Function("p",""
+"if(p){return p+'Hidden';}else{return'hidden';}");
s.vs=new Function("p",""
+"if(p){return p+'VisibilityState';}else{return'visibilityState';}");
s.ve=new Function("p",""
+"if(p){return p+'visibilitychange';}else{return'visibilitychange';}");
s.pvx=new Function("",""
+"s.pvt+=1;");
s.wpvc = function(){var tempDate = Date.now();s.Util.cookieWrite('s_tps',
Math.ceil((tempDate - s.totalTime)/1000));s.Util.cookieWrite('s_pvs', s.pvt)}
document.addEventListener('visibilitychange',function(event){if(document.hidden){s.visibility = false;clearTimeout(s.pvi);}else{s.visibility=true;s.pvi=setInterval(s.pvx,1000);}});s.totalTime=new Date();s.pvt=0;s.prefix=s.gbp;s.hidden=s.hp(s.prefix);s.visibility=true;s.visibilityState=s.vs(s.prefix);s.visibilityEvent=s.ve(s.prefix);
and added following rows to doPlugins function
if (s.c_r("s_tps") > 0)
s.eVar10= s.c_r("s_tps");
s.getPageVisibility();