Given that he's referencing B.B. King, and specifically playing "The Thrill is Gone" you can be certain he 's referring to the less aggressive picking technique of "soft attack". That's why he's said "turn your amp up loud" to compensate.

In note picking soft attack is a less aggressive striking of the string which is coincidentially more precise which diminishes the volume and affects the initial onset and development of sound. The rate at which the note develops, and its timbre.

Unsuprisingly, soft attack is the polar opposite of .....hard attack.

Personally, I prefer nylon plectrums when I'm seeking soft attack. Cheers.