I'm of awkwardly mixed opinions about this.
I doubt I could really have resisted the temptation myself, were I appropriately trained and armed.
On the other hand, the addtional player has just scragged the guy's panhandling shtick. And has make it even more clear that the guy's an amateur. Violates one of the first rules of jamming, that being to support the leading performer by playing under/behind them rather than hogging the spotlight, at least until invited to step forward and take a more leading part.
On the other other hand, I don't much like the captive-audience approach to panhandling (or preaching, which I got hit with a week or two ago). If you aren't good enough to draw an audience to you, don't get up in their faces when they can't walk away. So I'm not sure a bit of rudeness wasn't justified.
On the other other other hand, I'd MUCH rather have someone attempting to perform than delivering a sad-sack story. At least the guy's trying to deliver some value.
And every now and then you run across someone who really isn't looking for a handout and just thought it'd be cool to give folks a bit of a performance, Improv Everywhere style. Though doing that in a situation where the disinterested can't easily tune you out or walk away is a bit rude. Leave people room to not be part of the happening, if they don't want to be.
Like I say, mixed feelings... especially since this short video doesn't give us the whole story.