Pera,
I apologise for being a bit harsh. My thoughts are that Visual Separation is fine (I get it/comply with it often), but there must be adequate time for the aircraft that is being "asked" to do the staying clear to assess whether it is possible or not and then agree to it. In this case, not enough time was given, resulting in a very close encounter because the VFR could not take enough avoiding action to prevent a TCAS RA (which for Change 7, had to be close) as well, of course, his own significant bank away from the 777.
When the 777 got airborne, no separation standard existed. The controller had no options at all except to get the lighty to avoid the 777 visually. Had the controller been a few seconds later, or the VFR not picked up the 777... Too close for comfort.