There are a couple things there... one, there is actually something about war that is deeply fulfilling. Often, soldiers will say that they felt the most "alive" they've ever felt when in combat. Often, they will miss the war when it's over.
Yes, they'll talk about how shitty it is, in part because that's expected. They know it would sound weird to talk about missing it, but in it you gain a sense of camaraderie with your fellow soldiers that is unparalleled and there are moments in combat when you feel more "alive" than you ever have.
Granted, this is me talking as someone who has never seen combat myself. I'm not saying that combat is actually wonderful and war is idealized, just that this is actually pretty complicated and it's worth acknowledging that on some level there is something genuinely "cool" or attractive about war--we're all here out of some combination of morbid curiosity and a desire to get a sympathetic high. I've definitely cheered on some of the footage, though in this case I found myself actively calling out to them to get down. It's a wild interplay for me personally. I never really know when I click on a video if I'll be happy or horrified to see Russian soldiers dying. I know that they need to lose for Ukrainians to be safe and secure, but I'm glad I haven't dehumanized them. There's something really fascinating for me in the notion that the more I get caught up in hating "the enemy", the more I'm likely to become a mirror image of those who I hate.