For a start it is so harrowing knowing there's absolutely nothing they can do, SG-10 are just dead even though they're Right There and still trying to save themselves and this whole scene makes that feel so real, SG-10's deaths feel tragic in a way that doesn't happen for background characters a lot of the time in media (esp. 90s scifi)
Which makes a perfect backdrop for THIS CONVERSATION which is just so informative of both Sam and Jack's characters.
For Jack this is a reminder that while he's pragmatic and cynical a lot of the time, he so deeply cares about the people he works with and always puts them first, some theoretical scientific advancement isn't worth watching this tragedy play out. He spends so much of the early seasons being the "it sucks but we have to put the mission first" guy because he HAS to be that person but little moments like this one remind us he really really cares.
And for Sam, she's tunnel visioned on the impossible physics of the whole situation they're in, her mind's going a million miles an hour trying to explain how they're possibly witnessing time dilation play out in front of them, and she just completely forgets that there's real people out there dying on the other side of the gate. She's not even considered that they're watching a tragedy, she's zoned in on a problem and completely ignored everything else. And I'll bet she HATES that she suggested keeping the gate open. The moment Jack reminds her she's immediately agreeing with him, because she knows it's right, and she feels so guilty about it but she just didn't think.
I really like these little moments, and I think this is one of the most important scenes for Sam in the whole show. It's similar to Solitudes, when she zeroes in on trying to make the antarctic DHD work she never even thinks to try dialling an address other than Earth (which would have 100% worked) because she just tunnel visioned on one problem and forgot everything else. It's a really fun character flaw to give someone as intelligent as Sam is, especially with how much pressure she puts on herself. You just know she beat herself up about Jack almost dying in Solitudes knowing she could have saved him sooner if she'd just thought to dial anywhere other than Earth. And she absolutely feels so guilty about this moment too.