The guitarist is playing with an "EBow"! Does anybody remember those? They peaked in the 1980s.
I love this song (and this is a credible, if truncated, cover), but I'm kind of glad we're back to using the fingers of our left (right for Cobain, Hendrix, et. al.) hand to get the strings vibrating. I'd bet a decent sum of money that Scott Thurston employed old fashioned volume swells* in the original.
*Cf. Eddie Van Halen's "Cathedral" for a canonical example. Isaac Dinesen/Karen Blixen once wrote something to the effect that you've never truly lived until you've played this solo note-for-note in front of a four dozen or so intoxicated rednecks in a dilapidated rural AlabamaVFW hall.]