I'm taking this as a joke because I know that you know that youtube videos are capped at 30fps.

It's been verified by the developers themeselves. Try watching the Twitch stream this whole thread is based on.

edit: Christ, he's even given you the time at which point he says it.

Well yes but you can definitely tell the differences from gameplay in most cross-gen vids, like this one.

Just not in the Lara Croft one since its third person?

I know, Amos is the same one who said it during the stream right? 

He says it twice and even mentions how smooth it makes it look. It's also been verified over at Gaf:

Verified sources close to Rocket Chainsaw have detailed performance and rendering quality of both the Xbox One and PlayStation builds of Tomb Raider: Definitive Edition. And for that we’re thankful. So here it is!

On average:
PlayStation 4 = 60 fps
Xbox One = 30 fps

Yes, the PlayStation 4 build is, on average, twice the framerate of the Xbox One build. Both builds are rendering at native 1080p resolution, and generally look the same in graphical effects (though some minor differences may apply). Performance is a different matter. Both feature unlocked framerates, meaning framerate fluctuates between higher and lower values. The Xbox One build can technically reach around 45 fps, though this performance is generally only achieved during the most empty, simplest environments. For most of your play, and during action scenes, the Xbox One build will sit on around 30 fps. On the other hand, the PlayStation 4 build will attempt to hit 60 fps as often as possible, and does a pretty good job of doing so, but does have slight dips under 60 fps during certain scenarios.

So there it is. Both 1080p. PlayStation 4 = ~60fps average. Xbox One = ~30fps average. Take with a grain of salt if you’d like, but we’ve confirmed it on our end, and confirmation for the rest of the world is only a week away.

The source is a trusted source:

http://www.rocketchainsaw.com.au/exclusive-tomb-raider-definitive-edition-ps4xone-framerates-revealed/

This is OVER! Microsoft had no idea!

Is anyone besides rocketchainsaw confirming the difference between the two or is everyone using them as a source?

The mod that started that thread would not have started it if he wasn't 100% certain it was true. And listen to the Twitch feed again. He goes out of his way to avoid talking about the X1 version. He could have easily taken the opportunity to tell us it was running on the X1 at 60fps too, after all, he wants to promote both versions. Clearly he couldn't and it's obvious why.

An insider has also mentioned 'another' multiplatform game is reportedly in a similar situation, so we'll probably hear about that soon too. My guess would be Watch dogs.

So the PS4 version is the more definitive version.

2 reasons why you can't see much of a difference in the TR video.

The head to head gameplay scenes are too short to make something out.

The video was produced before the last framerate optimization.

But color me surprised that I can actually see the FPS difference in the BF comparison.