Who uses silver solder? What a dumb place to spend your money. Good flux and 60/40 is all you need.
It depends what you are working with, doesn't it? Some components, PCBs , connectors and wires in older Tektronix oscilloscopes and other RF equipment are plated with silver. There you would use the silver bearing solder I believe (to prevent silver scavenging).
Silver bearing solder is expensive compared to lead free and standard SnPb solder but I would not go as far as to say spending money on it is wasted. If you don't need it OK, no point arguing
Silver bearing solder does have a lower resistance though, and has a better reliability compared to non-silver Rohs and 60/40 tin/lead solder. The reliability here is regarding thermal fatigue and mechanical strength of the joint. Note, that this is only true for solder with lead, too little is known about the impact of silver and copper in Rohs solder regarding thermal fatigue at this point.
Silver is added to RoHS solder to lower the melting point and improve wetting. Silver in RoHS solder makes it more likely to fail to mechanical shocks but improve resistance to thermal fatigue (at least, better than RoHS solder without silver).
I use Sn62Pb36Ag2 solder for SMD work, and also have about 2kg of 0.5mm 60/40 solder. I believe I'm biased towards the silver bearing solder.
What I don't understand is, he says his solder is lead free and calls it silver solder. If it's one of those 3.5-4% silver bearing solders that melt at 180-200 °C / 400 °F, why does he have to heat his solder iron up for 20 minutes
(well, that black tip says it all)
EDIT: he didn't claim his solder is lead free. No idea why I thought he did.