She has every right to be upset. But the links she's making are tenuous at best. The Ilhan Omar situation has zero fuck all to do with the NZ terrorist attacks. That's not the rhetoric that the shooter and co. were influenced by. The point she's trying to make you would need two planes, a bus ride and a walk through the backwoods to get there.
I agree that Ilhan Omar has been treated poorly by both colleagues and the media. There is most likely some Islamophobia in there as well. But the diet racism on display is not what white nationalists and white supremacists are feeding from.
I watched the video in the OP and it seems to cut off fairly soon. I dunno if there was more exchange going on afterwards. But it's good she was able to get her frustrations out and that CC let her do so. I wouldn't necessarily call it a harassment, but maybe a bit in poor taste for the time/place. But I'm not going to police someone who is clearly frustrated and fed up on their behavior. She saw her opportunity and she went for it.
Not keen on the donation begging afterwards. I hope the reports of it being a fake account are true. It would definitely sour me on the situation unless those donations are going for a good charity, maybe even one related to the NZ mosques and Muslim community.
Edit: The age thing, at 20 yeah you are a young person but you are also an adult and thus responsible for your actions. Not personally judging her harshly for reasons stated above. And she herself does not deserve online harassment and what that entails. Criticism fine; discourse about what she's said, okay, harassment and hate speech absolutely not. That goes for someone of any age.