Eh, I think vids are more useful and then doesn't ruin the experience of performing the fight yourself, which I think was one of the original topics the OP mentioned. A vid you can skip through quickly to learn the fight, which I appreciate guildies doing because it cuts down on the time it takes to learn and down a boss. On the other hand, LFR might make raiders overconfident or complacent. "Oh, this boss, I can just afk and autoattack." Not the mentality you'd like in a raider.
But doing LFR doesn't give you the experience of doing the fight since so many mechanics are nerfed/removed. How does doing LFR Stone Guards ruin the experience of doing the fight? The LFR version is just a big AoE fest with pretty much no mechanics.
LFR ruins the fight only in that you can see it. Which also happens with vids of heroic kills. But with the heroic vid, you actually see the whole fight instead of the nerfed LFR version.
BTW, there have always been bad raiders who can't do the mechanics. Back in my day, we took them on some trial runs, saw that they were incompetent, then dropped them. It's even easier now because you can take them into a LFR, log it, see that they suck and have no clue about mechanics, and drop them. That way you don't even have to bring them into a real raid.
It ended for me when toggled hardmodes were introduced in ToC. I love the Ulduar style hardmodes but despise the UI option to make monsters hit harder and drop shinier purples.
I did enjoy the pre ToC system where you had to do something extra or in fight to prompt a hardmod rathethen just having somebody that killed it in norm in the group and flipping a switch.
I do feel the LFR system we have in place is just like a trade troll filled tutorial on the raid. Somi that you can do with 1/3rd of the group afk and it doesn't effect things is bad news.
Beware of the man who works hard to learn something, learns it, and finds himself no wiser than before... He is full of murderous resentment of people who are ignorant without having come by their ignorance the hard way. -Kurt Vonnegut, "Cat's Cradle"